SCIBERRAS, A. (2013) Fauna regarded as domestic pests in the Maltese Islands - The Flies

The Flies
By Arnold Sciberras

It is a fact that the most hated of all insects are the cockroaches. Second runner-ups are the flies.The true flies are insects, scientifically known as Diptera which means two winged species. In reality they have also two pairs of wings like most other orders of insects but the second pair called halters are small knobbed structures modified from the hind wings. They are flapped rapidly and function as accelerometers to help the insect maintain stability in flight. The presence of a single pair of wings distinguishes true flies from other insects with the common name ending as "flies". On unfrequent occasions some species of flies became wingless.

This large group consists of around 120,000 species worldwide but it is believed that more of the same amount are still not described, It is one of the major insect orders both in terms of ecological and human (medical and economic) importance. While the majority known are beneficial and of great importance to their local ecosystems only a dozen or so species are associated with human habitations while about ahandful species are well known as pests. It is yet unknown how many species exist in the Maltese islands as new species are found frequently but a very rough estimate from local literature indicates that till 1995 over 218 species from 19 families were already known locally. Others have been recorded since. With these endemic species are included such as The Schembri`s Spider fly (Ogcodes schembrii) Dubbiena tal-Brimb ta`Schembri.

Flies are well adapted for aerial movement, and typically have short and streamlined bodies. They have a mobile head with eyes, and, in most cases, have large compound eyes on the sides of the head, with fives small ocelli on the top. The antennae take a variety of forms, but are often short, to reduce drag while flying. Flies consume only liquid food, and their mouthparts and digestive tract show various modifications for this diet. The majority of species spit out saliva on solid foods to predigest it, and then suck it back in. They also regurgitate partly digested matter and pass it again to the abdomen. The most apparently primitive flies have piercing blade-like mandibles and fleshy palps, but these have become adapted into numerous different forms in different groups. These include both the fine stilleto-like sucking mouthparts of mosquitoes, and the fleshy proboscis of houseflies. The gut typically includes large diverticulae (outpouching of a hollow or a fluid filled structure )allowing the insect to store small quantities of liquid after a meal.

When flies mate, the male initially flies on top of the female, facing in the same direction, but then turns round to face in the opposite direction. In some species, this forces the male to lie on its back in order for its genitalia to remain engaged with those of the female, but in most cases, the torsion of the male genitals allows the male to mate while remaining upright. This leads to flies having more reproduction abilities than most insects and at a much quicker rate. This is why the flies come in great populations due to their ability to mate effectively and in a short period of time during the mating season.

The female lays her eggs as close to the food source as possible and development is generally rapid, allowing the larva to consume as much food as possible in a short period of time before transforming into the adult. In extreme cases, the eggs hatch immediately after being laid, while a few flies are ovoviviparous, (bear live young) with the larva hatching inside the mother
Aside from their bad reputation, there are practical roles that flies can play (e.g., flies are reared in large numbers in Japan to serve as pollinators of sunflowers in greenhouses), especially the maggots (young) of various species. Some types of maggots found on corpses have been found to be of great use to forensic scientists; specifically Forensic Entomology. By their stage of development, these maggots (and other insects) can be used to give an indication of the time elapsed since death, as well as the place the organism died. The lack of maggot presence is also telling in an investigation. Maggot species can be identified using their DNA. The size of the house fly maggot is 10–20 mm. At the height of the summer season, a generation of flies (egg to adult) may be produced in 12–14 days. Some other families of Insecta, feed on maggots. Thus, the lack of maggots would increase the estimated time of death. Other types of maggots are bred commercially, as a popular bait in angling, and a food for carnivorous pets such as reptiles or birds. Maggots have been used in medicine to clean out necrotic wounds and in food production, particularly of cheeses designed to rot as part of their 'aging' process.

On the other hand the House, Blue, Green and Flesh flies can be very loyal to our establishments and these are the ones that should be treated as pests. As a world wide perspective Diptera, in particular the mosquitoes (Culicidae), are of great importance as disease transmitters, acting as vectors for malaria, dengue, West Nile virus, yellow fever, encephalitis and other infectious diseases.

The Common housefly (Musca domestica), Dubbiena tad-Djar is the most common of all domestic flies, accounting for about 90% of all flies in human habitations, and indeed one of the most widely distributed insects. The adults are 8–12 mm long. Their thorax (second part of the insect`s body)is gray, with four longitudinal dark lines on the back. The underside of their abdomen is yellow or whitish in color, and their whole body is covered with hair-like projections. The females are slightly larger than the males, and have a much larger space between their red compound eyes. The mass of pupae can range from about 8 to 20 mg under different conditions. Each female fly can lay approximately 500 eggs in several batches of about 75 to 150. The eggs are white and are about 1.2 mm in length. Within a day, larvae (maggots) hatch from the eggs; they live and feed in (usually dead and decaying) organic material, such as garbage etc. They are pale-whitish, 3–9 mm long, thinner at the mouth end, and have no legs. They live at least one week. Later, the maggots crawl to a dry cool place and transform into pupae, colored reddish or brown and about 8 mm long. The adult flies then emerge from the pupae. The adults live from two weeks to a month in the wild. After having emerged from the pupae, the flies cease to grow; small flies are not young flies, but are indeed the result of getting insufficient food during the larval stage.

Some 36 hours after having emerged from the pupa, the female is receptive for mating. The male mounts her from behind to inject sperm. Copulation takes between a few seconds to a couple of minutes. Normally the female mates only once, storing the sperm to use it repeatedly for laying several sets of eggs. Males are territorial: they will defend a certain territory against other males and will attempt to mount any females that enter that territory.

The Blue Bottle fly (Calliphora vomitoria) Zarzura is a very common fly found in most areas of the world. It is 10-14 mm long, slightly larger than a housefly. The head and thorax are dull gray and the abdomen is bright metallic blue with black markings. Its body and legs are covered with black bristle-like hair. The eyes are red and the wings are clear. The legs and antennae are black and pink. The chest is bright purple and has spikes to protect themselves against other flies. A female blue bottle fly lays her eggs where she feeds, usually in decaying meat, garbage, or faeces. Pale whitish larvae, commonly called maggots, soon hatch from the eggs and immediately begin feeding on the decomposing matter where they were hatched. After a few days of feeding, they are fully grown. At that time they will crawl away to a dry place where they can burrow into soil or similar matter to pupate into tough brown coccoons. After two or three weeks, the adults emerge to mate, beginning the cycle again. During cold weather, pupae and adults can hibernate until warmer temperatures revive them. They are also pollinators of some flowers with a strong odor such as The Fringed Rue (Ruta chalepensis) Fejgel.

The Green Bottle fly (Lucilia sericata). Dehbija tal-Hmieg.The maggots of this fly are known to preferentially consume dead tissue while leaving live tissue intact, and so have been sold for use in maggot therapy, primarily during the years before the widespread use of antibiotics and medicines and in modern times due to a resurgence of medical literature documenting their effectiveness. These flies are known to lay eggs in cadaver tissue in the wild within hours after death. The developmental stage of their larvae in the cadaver can be used to accurately predict the time death occurred. They are also generally found on faeces and also wild flowers. When specimens become old its green metallic color may change to red.

Another common house hold pest is The Fertoni flesh fly (Sarcophaga fertoni) Dubbiena Tal –Laham.as the common name implies this species breeds in carrion but also in dung or decaying material, in some cases also lay their eggs in the open wounds of mammals. These larvae, commonly known as maggots, live for about 5-10 days, before descending into the soil and maturing into adulthood. At that stage, they live for 5-7 days.

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SCIBERRAS, A. (2013) Fauna regarded as domestic pests in the Maltese islands - The Rodents

The Rodents
By Arnold Sciberras

The Europeans’ only associations with these creatures are generally negative. For instance, "Rats!" is used as a substitute for various vulgar interjections in the English language. These associations are not drawn, per se, from any biological or behavioural trait of these animals, but possibly from the association of rats (and fleas) with the 14th-century medieval plague called the Black Death. Rats for example are seen as vicious, unclean, parasitic animals that steal food and spread disease. Folklore, especially the local one, has also played its part. However, on the other side of the world, in Indian tradition, rats are recognized as the vehicle of Lord Ganesh and a rat's statue is always found in a temple of Ganesh. In the north-western Indian city of Deshnoke, the rats at the Karni Mata Temple are held to be destined for reincarnation as Sadhus (Hindu holy men). The attending priests feed milk and grain to the rats, the pilgrims of which also partake. Eating food that has been touched by rats is considered a blessing from god. The indigenous rats are allowed to run freely throughout the Karni Mata temple.

Rodentia is an order of mammals also known as rodents, characterized by two continuously growing incisors (front teeth), two on the upper and lower jaws respectively, which must be kept short by gnawing. This is the origin of the name, from the Latin word rodere, which means to gnaw. These teeth are used for cutting wood, biting through the skin of fruit, or for defence. The teeth have enamel on the outside and exposed dentine on the inside, so they self-sharpen during gnawing. Rodents lack canines, and have a space between their incisors and premolars.

Forty percent of mammal species world-wide are rodents (around 2,277 species). They are found in vast numbers present nearly on all continents and islands, and in all habitats except oceans and Antarctica. Their success is probably due to their small size, short breeding cycle, and ability to gnaw and eat a wide variety of foods. (Lambert, 2000). Common rodents include mice, rats, squirrels, porcupines, beavers, chipmunks, guinea pigs, and voles. Rodents have sharp incisors that they use to gnaw wood, break into food, and bite predators. Most eat seeds or plants, though some have more varied diets.

Many rodents are small; the tiny African pygmy mouse (Mus minutoides) can be as little as 6 cm in length and 7 g in weight at maturity. On the other hand, the Capybara (Hydrochoerus hydrochaeris) can weigh up to 80 kg, and it is in fact the largest known rodent present today. The extinct One tonne- Rat (Josephoartigasia monesi), is estimated to have weighed about 1,000 kg, and possibly up to between 1,534 kg or 2,586 kg.

Nearly all rodents feed on plants, seeds in particular, but there are a few exceptions which eat insects or fish. Some squirrel species are known to eat passerine birds like cardinals and blue jays.

Rodents are important in many ecosystems because they reproduce rapidly, and can function as food sources for predators, mechanisms for seed dispersal, and as disease vectors. Humans use rodents as a source of fur, as pets, as model organisms in animal testing, for food, and even for detecting landmines.

The fossil record of rodent-like mammals begins shortly after the extinction of the non-birdlike dinosaurs 65 million years ago. Some molecular clock data, however, suggests that modern rodents had already appeared around 90 million years ago, although other molecular divergence estimations are in agreement with the fossil record.

In the Maltese Islands four species of rodents are known to occur. These are later divided in 2 species of rats and 2 species of mice. Rats are typically distinguished from mice by their size; rats are generally large rodents, while mice are generally small rodents. The best-known rat species (and these are what we have in our islands) are the Black Rat (Rattus rattus) and the Brown Rat (Rattus norvegicus). The group is generally known as the Old World rats or true rats, and originated in Asia. Rats are bigger than most Old World mice, which are their relatives, but seldom weigh over 500 grams in the wild. Male rats are generally called bucks, unmated females are called does, pregnant or parent females are called dams, and infants are called kittens or pups. A group of rats is either referred to as a pack or a mischief.

In some developed countries, many people keep domesticated rats and mice as pets. Regarding rats, these are of the Brown Rat species which originated in the grasslands of China and have spread to Europe and eventually, in 1775, to the New World. Pet rats are Brown Rats descended from those bred for research, and are often called "fancy rats", but are the same species as the common city "sewer" rat. Domesticated rats tend to be both more docile than their wild ancestors and more disease prone, presumably due to inbreeding.

These common species are opportunistic survivors and often live with and near humans, therefore they are known as commensals. They may cause substantial food losses, especially in developing countries. Wild rats and mice can carry many different "zoonotic" pathogens, such as Leptospira, Toxoplasma gondii and Campylobacter, and may transfer them to other species, for example to humans. The Black Death is traditionally believed to have been caused by the micro-organism Yersinia pestis, carried by the Tropical Rat Flea (Xenopsylla cheopis) which parasitized on Black Rat living in European cities during the epidemic outbreaks of the Middle Ages; these rats were used as transport hosts. Today, this cycle still exists in many countries of the world and plague outbreaks still occur every year. Besides transmitting zoonotic pathogens, rats are also linked to the spread of contagious animal pathogens that may result in livestock diseases such as Classical Swine Fever and Foot-and-mouth disease. The normal lifespan of rats ranges from two to five years, and is typically three years.

Although mice may live up to two and a half years in captivity, the average mouse in the wild lives only about four months or so primarily owing to heavy predation. Cats, dogs, birds of prey, snakes and even certain kinds of arthropods have been known to prey heavily upon mice. Nevertheless, due to its remarkable adaptability to almost any environment, the mouse is one of the most successful mammalian genera living on Earth today.

Taking a closer look at our local mice the most common and the most regarded as a nuisance is the House Mouse (Mus musculus). This species has an adult body length (nose to base of tail) of 7.5–10 cm and a tail length of 5–10 cm. The weight is typically not more than 10–25 g. They vary in colour from grey to light brown (wild form). They have short hair and a light belly. The ears and tail have little hair. The hind feet are short yet they can jump up to 45 cm at one go. The droppings are blackish, about 3 mm long and have a strong musty smell. There are 5 subspecies scientifically recognised.

House mice thrive under a variety of conditions: they are found in and around homes and commercial outlets as well as in open fields and agricultural lands. House mice consume and contaminate food meant for humans, pets, livestock, or other animals. In addition, they often cause considerable damage to structures and property. They can transmit pathogens that cause diseases such as salmonellosis, a form of food poisoning.

Young males and females are not easily distinguished: females have a significantly smaller distance between their anus and genital opening. Females have 5 pairs of mammary glands and nipples; males have no nipples. When sexually mature the most striking and obvious difference is the presence of testicles on the males. These are large compared to the rest of the body and can be retracted into the body.

House mice usually run, walk or stand on all fours; but when eating, fighting or orienting themselves, they stand only on the hind legs, supported by the tail. When running the horizontal tail serves for balance; the end stands up vertically, unless the mouse is frightened. Mice are good jumpers, climbers, and swimmers.

Primarily nocturnal animals, mice compensate for their poor eyesight with a keen sense of hearing, and rely especially on their sense of smell to locate food and avoid predators. They live in a wide variety of hidden places that are near food sources and construct nests from various soft materials. Mice are territorial and one dominant male usually lives together with several females and young. Dominant males respect each other's territory and normally enter another's territory only if it is vacant. House mice primarily feed on plant matter, but they will also accept meat and dairy products. Although they are generally known to like fruits, they are repelled by the scent of many varieties of artificial fruit scent, for example strawberry or vanilla-scented candles. The reason for this is unknown, although it dates back to antiquity when Roman Senators used candles scented with strawberry oils to keep mice out of their sleeping chambers. They drink water but require little of it, relying mainly on the moisture present in their food. They sometimes eat their droppings to acquire nutrients produced by bacteria in their intestines. House mice, like other rodents, do not vomit.

Mice are afraid of rats, which often kill and (partially) eat them. This rat behaviour is known as muricide. Despite this behaviour, free-living populations of rats and mice do exist together locally. House mice are generally poor competitors and in most areas cannot survive away from human settlements in areas where other small mammals, such as wood mice, are present]

Female house mice have an oestrous cycle that is 4–6 days long, with oestrus itself lasting less than a day. If several females are held together under crowded conditions they will often not have an oestrus at all. If they are then exposed to male urine, they will have an oestrus after 72 hours. Following copulation, female mice will normally develop a vaginal plug which prevents further copulation. This plug stays in place for some 24 hours. The gestation period is about 19–21 days, and they give birth to a litter of 3-14 young (average 6-8). One female can have some 5-10 litters per year, so their population can increase very quickly. Breeding occurs throughout the year (however, animals living in the wild do not reproduce in the colder months, even though they do not hibernate). The newborn are blind and without fur. Fur starts to grow some three days after birth and the eyes open one to two weeks after birth. Females reach sexual maturity at about 6 weeks and males at about 8 weeks, but both can breed as early as five weeks.

The Wood Mouse (Apodemus sylvaticus), is an uncommon species locally and tends to be much harder to locate. If a wood mouse is caught by its tail, it can quickly shed the end of it, which may never re-grow. .In spite of its name, it prefers hedgerows to woodland. Wood mice inhabit wood, grasslands, and cultivated fields. Almost entirely nocturnal and terrestrial, Wood Mice burrow extensively, build nests of plants and live in buildings during harsh seasons.

The latter are primarily seed eaters, particularly seeds of trees. If there is a plentiful amount of seeds on the ground, they carry them back to their nests/burrows for storage. They may eat small invertebrates such as snails and insects, particularly in late spring and early summer when seeds are least available. They also consume berries, fruits and roots. They do not hibernate, however during severe winter seasons they fall into a sort of torpor – a decrease in physiological activity. They are mainly active during the night, and are very good climbers. While foraging, the Wood Mice pick up and distribute visually conspicuous objects, such as leaves and twigs, which they then use as landmarks during exploration. The gestation period of wood mice is of 25–26 days and each female produces, on average, 5 young. The offspring become independent after about three weeks and become sexually active after two months. It is often confused with the House Mouse and although it is not that much of a pest, since its status is still much unknown locally, it usually ends up with the same fate.

Not to be mistaken as rodent pests, local beneficial species not related to rodents, such as the Pygmy White Toothed Shrew (Suncus etruscus) (regarded as the smallest mammal in the world) and the Sicilian Shrew (Crocidura sicula) (endemic to Sicily and Gozo), usually also end up with the same fate. These are more closely related to hedgehogs rather than to rats and mice and are beneficial to us as they keep pest insects at bay. They are also protected by law.

As subjects of scientific research, rats and mice have been used in all possible ways and are model organisms for scientific research. The more they are studied, the more we see that their psychology and homology, in many ways, seem to be similar to humans more than we could even imagine.



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SCIBERRAS, A. (2013) Fauna regarded as domestic pests in the Maltese islands - The Bed bugs

The Bed Bugs

By Arnold Sciberras

Instead of going to bed after a long day to get a goodnight sleep and well deserved rest, this period off can easily turn into an itching nightmare if accompanying you in bed is the creature this article is dedicated to. 

Bedbugs are small, elusive, and parasitic organisms all belonging to a family of insects called Cimicidae. They live strictly by feeding on the blood of humans and other warm-blooded animals (such as other mammals and birds). The name 'bed bug' is derived from the insect's preferred habitat, infesting houses and especially beds or other common areas where people may sleep. These insects may also be found on carpets and other areas where host is present. Bedbugs, though not strictly nocturnal, are mainly active at night and are capable of feeding on their hosts without being noticed. The number of species of bedbugs has been estimated to be anywhere between 75 and 108. Most species only feed on humans when other prey is unavailable. In Malta the species number is yet unknown but the most cosmopolitan species are presumed present.the only species till now recorded locally is Cimex lectularius. The latter locally is mosly found in hotels but recently populations have exploded and several cases were reported from private homes. Bedbugs are true insects and not arachnids, unlike other pests such as dust mites and ticks.

Adult bedbugs are reddish-brown, flattened, oval, and wingless. Bedbugs have microscopic hairs that give them a banded appearance. A common misconception is that they are not visible to the naked eye. Adults grow to 4–5 mm in length and 1.5–3 mm in width. They do not move quickly enough to escape the attention of an observer. Newly hatched nymphs are translucent, lighter in color and become browner as they moult and reach maturity. They use pheromones and kairomones to communicate regarding nesting locations, attacks, and reproduction.

The life span of bedbugs varies by species and is also dependent on feeding. Bedbugs are bloodsucking insects. They are normally out at night just before dawn, with a peak feeding period of about an hour before sunrise. Bedbugs may attempt to feed at other times if given the opportunity and have been observed feeding during all periods of the day. They reach their host by walking, or sometimes climb the walls to the ceiling and drop down on feeling a heat wave. Bedbugs are attracted to their hosts by warmth and the presence of carbon dioxide. The bug pierces the skin of its host with two hollow feeding tubes. With one tube it injects its saliva, which contains anticoagulants (so blood will not cloth) and anesthetics (so you don’t feel them), while with the other it withdraws the blood of its host. After feeding for about five minutes, the bug returns to its hiding place. The bites cannot usually be felt until some minutes or hours later, as a dermatological reaction to the injected agents, and the first indication of a bite usually comes from the desire to scratch the bite site. Due to their natural aversion for sunlight, bedbugs come out at night.

All bedbugs mate via a very cruel like process called traumatic insemination. Instead of inserting their genitalia into the female's reproductive tract as is typical in copulation, males instead pierce females with hypodermic genitalia and ejaculate into the body cavity

Although bedbugs can live for a year or eighteen months without feeding, (1 species purportedly up to three years) they normally try to feed every five to ten days. Bedbugs that undergo dormancy due to lack of food often live longer than a year, while well-fed specimens typically live six to nine months.

Bedbugs travel easily and quickly along pipes and boards, and their bodies are very flat, which allows them to hide in tiny crevices. In the daytime, they tend to stay out of the light, preferring to remain hidden in such places as mattress seams, mattress interiors, bed frames, nearby furniture, carpeting, between the pages of books, baseboards, inner walls, tiny wood holes, and/or room clutter. Bedbugs can be found solitarily, but will more often congregate in groups once established. They tend not to travel further than 30 meters from their host to feed and will usually remain close to their blood supply in the same bedroom or living quarters where people sleep.

Exact nesting locations of a typical infestation can vary greatly as bedbugs will often attempt to hide themselves within a wide range of tiny areas or spaces, within cracks and crevices, or simply in darker locations where they are out of plain sight. Such hiding spots may not always be immediately obvious to an inexperienced searcher – although bedbugs will indeed be much easier to find and locate once an infestation has become concentrated. A standard mattress, however, is most likely to house bedbugs along the sewn piping material running along the outer edges on both the top and bottom sides of the mattress. Bedbugs may also quietly nest themselves under the cover of various materials and lie completely still for long periods making detection even more difficult.

The potential places where a typical bedbug may choose to hide are numerous. It is, however, very common for bedbugs to nest in whatever furniture it is that a person sleeps and naps on—which is not at all limited to beds, but also includes upholstered chairs, loveseats, sofas, plush furniture, futons, etc., as well as other non-traditional beds such as camping cots, floor pads, hide-a-beds, bean bags, cradles, etc. Bedbugs will attempt to nest in any of these sleeping structures if given the opportunity and will take cover in nearby areas as well (sleeping directly on the floor, for example, may cause them to feed but then nest in the nearby carpeting and furniture). Bedbugs tend to want to hide as close as possible to where they feed. If a person sleeps on a couch in a room where bedbugs are present, for example, then it could be generally expected that the bedbugs in the given room would quickly find their way onto the sofa as well as onto the sleeping person where they may then feed (i.e. unless the couch had been effectively segregated or isolated beforehand to prevent bedbugs from crawling onto it). Then, upon the sleeping host providing a blood meal, it could be expected that the engorged bedbugs will attempt to make the couch itself their nesting location; with the bugs congregating under the sofa, in the seams and folds of the fabric, in the crevices, in the creases atop and behind the headrest, amongst the armrests, in the cushions, in the wooden assembly, etc. Usually bedbugs do not wander too far from their meal. And this process of searching out a host, honing in to feed, then hiding in immediate and nearby crevices can take place over the course of a single night and, in such a manner, a couch or an upholstered chair may become heavily infested with bedbugs within a very short time.

Reactions to bedbug bites may appear indistinguishable from mosquito bites although they tend to last for longer periods. Bites may not become immediately visible and can take up to nine days to appear. Bedbug bites tend not to have a red dot in the center such as is characteristic of flea bites. A trait shared with flea bites is tendency towards the pattern of sequential bites often aligned in rows of three. This may be caused by the bedbug being disturbed while eating and relocating half an inch or so further along the skin before resuming feeding. Alternatively, the arrangement of bites may be caused by the bedbug repeatedly searching for a blood vein.



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SCIBERRAS, A. (2013) Fauna regarded as domestic pests in the Maltese islands - The Woodlice

The Woodlice
By Arnold Sciberras

If there is a high level of humidity in your house then one of your residents must be the tank- like packed creature commonly known as the woodlouse. This friend of ours is a crustacean (same group which includes such familiar animals as crabs, lobsters, crayfish, shrimp, krill and barnacles). The latter hosts 50,000 described species till now and Woodlice is just one suborder of this group called Oniscidea within the order Isopoda, with over 3,000 world-wide known species. Generally, woodlice are identified by their rigid, segmented, long exoskeletal and fourteen jointed limb body. The number of local species is still uncertain, but the level of interest is high as some species like Maltese Wood louse, Armadillidium schmalfussi, Hanzir l-Art ta’ Malta and Maltese Cave Dwelling Wood louse, Armadillidium aelleni, Hanzir l-Art tal-Gherien ta` Malta are endemic to our archipelago and the latter, as name implies, is confined to caves.

Woodlice need moisture because they breathe through gill like structures called pseudo-trachea, and thus are usually found in damp, dark places, such as under rocks, wood or in our basements. They are usually nocturnal (night dwellers) and are detritivores, i.e. they feed mostly on dead plant matter, though they have been known to feed on cultivated plants, such as ripening strawberries and tender seedlings. Woodlice are ecologically very important because their mode of feeding ultimately leads to a faster replenishment of nutrients back to the soil. In artificial environments such as greenhouses where it can be very moist, woodlice may become abundant and damage young plants.

As already mentioned, these creatures have a shell-like exoskeleton, which must progressively shed as it grows. The moult takes place in two stages; the back half is lost first, followed by the front half which takes two to three days to shed. This method of moulting is different from that of most arthropods, which shed their cuticle in a single process.

A female woodlouse will keep fertilized eggs in a marsupium on the underside of her body until they hatch into small, white offspring. The mother then appears to "give birth" to her offspring.

Some species of woodlice are able to roll into a ball-like form when threatened by predators, leaving only their armoured back exposed. This ability, or dominant behaviour, explains many of the woodlouse's common names. Woodlice in the genus Armadillidium can roll up into an almost perfect sphere as a defensive mechanism; hence some of the common names such as pill bug or roly-poly. Most woodlice, however, cannot do this.

Metabolic rate is temperature dependent in woodlice. In contrast to mammals and birds, invertebrates are not "self heating": the external environmental temperature relates directly to their rate of respiration. They are generally not regarded as a serious household pest, as they do not spread disease and do not damage wood or structures; however, their presence can indicate dampness problems and their number may become irritating to the house owners.

Woodlice are eaten by a wide range of insectivores, but the only animals known to prey exclusively on woodlice are spiders of the genus Dysdera.

Pill-bugs (woodlice of the family Armadillidiidae) are usually confused with pill millipedes. Although they are distantly related to one another, the two are taxonomically distinct.

Both of these groups of terrestrial segmented arthropods are about the same size. They live in very similar habitats, and they can both roll up into a ball. Pill millipedes and pill-bugs appear superficially similar to the naked eye. This is an example of convergent evolution (the acquisition of the same biological trait in unrelated lineages).

Pill millipedes can be distinguished from woodlice on the basis of having two pairs of legs per body segment instead of one pair like all isopods. Pill millipedes also have thirteen body segments, whereas the woodlouse has eleven. In addition, pill millipedes are smoother, and resemble normal millipedes in overall colouring and the shape of the segments.

Besides the Common Maltese Woodlouse which one may occasionally find in a residence, the Common Woodlouse, Armadillidium vulgare, Hanzir l-Art Komuni is the most familiar one in establishments and unfortunately the one which regarded the most as a pest. These creatures are harmless and also beneficial but are regarded as pests because they tend to congregate in large numbers. On some hose facades each year thousands cover the facades during the evening and then disperse or die out in the morning. This behaviour is still a phenomenon not understood. This species may reach a length of 18 mm, and is capable of rolling into a ball when disturbed. This ability, along with its general appearance, gives it the name pill-bug and also creates confusion with pill millipede species.

This species is able to withstand drier conditions than many other woodlouse species, and is mostly found in calcareous soils or coastal areas. It feeds chiefly on decaying plant matter, but also grazes lichens and algae from tree bark and walls.

It is able to regulate its temperature through its behaviour, preferring bright sunshine when temperatures are low, but remaining in shadow when temperatures are high; temperatures below −2 °C or above 36 °C are lethal to it. The latter is also less susceptible to cold during the night, and may enter a state of dormancy during the winter in order to survive temperatures which would otherwise be lethal.



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SCIBERRAS, A. (2013) Fauna regarded as domestic pests in the Maltese islands - The Myriapods

The Myriapods

By Arnold Sciberras

As someone at home steps on a creature that instantly releases a foul smell, that present organism defiantly belongs to this group on which the article is about. Myriapoda is a group (subphylum) of arthropods( which also includes insects, arachnids and crustaceans) containing millipedes, centipedes, and others. The group has 13,000 species known, all of which are terrestrial (land dwellers). Although their name suggests they have myriad (10,000) legs, Myriapods range from having over 750 in some species to others having fewer than ten legs.

Myriapods have a single pair of antennae and, in most cases, simple eyes. The mouthparts lie on the underside of the head. A pair of mandibles lie inside the mouth. Myriapods breathe through spiracles (holes on the exterior that let air in) that connect to a tracheal system similar to that of insects. There is a long tubular heart that extends through much of the body, but usually few, if any, blood vessels.

During mating, male myriapods produce a packet of sperm, or spermatophore, which they must transfer to the female externally; this process is often complex and highly developed. The female lays eggs which hatch as much shortened versions of the adults, with only a few segments and as few as three pairs of legs. The young add additional segments and limbs as they repeatedly moult to reach the adult form.

Myriapods are most abundant in moist locations, where they fulfill an important role in breaking down decaying plant material, although a few live in grasslands, semi-arid habitats or even deserts. Most species like millipieds eat plant or decaying matter, with the exception of centipedes, which are chiefly nocturnal predators. Pauropodans and symphylans are small, sometimes microscopic animals that resemble centipedes superficially and live in soils. Millipedes differ from the other groups in having their body segments fused into pairs, giving the appearance that each segment bears two pairs of legs, while the other three groups have a single pair of legs on each body segment. Although not generally considered dangerous to humans, many myriapods produce noxious secretions which can cause temporary blistering and discolouration of the skin.

Centipedes make up the order Chilopoda. They are fast, predatory and venomous, hunting mostly at night. There are around 3,300 species .they can range from species not exceeding 12 mm to others which may exceed 30 cm. About 16 species have been recorded from the Maltese islands.. Common encounters can be with the following 3 species:

The Soil Centipede Himantharium gabrielis Xini Tal-Hamrija is quite a docile species and is restricted to soil environments. It is easily found in gardens and under pots. Very beneficial in controlling a number pest species.

The Yellow Banded Centipede Scolopendra cingulata Xini Isfar is one of the smallest members of the scolopendra family at approximately 10-15 cm. They are easily recognized by the alternating bands of black and yellow/gold.

The head of this centipede has a pair of antennae, jaw-like mandibles, and other mouth parts. Each segment has one pair of legs. The front segment has a pair of venomous claws (called maxillipedes) that are used for both defense and for capturing and paralyzing prey. The venom is less toxic than other scolopendrid centipedes, but still quite painful. they are still fast moving and can be aggressive so it's best just to look at these colorful creatures rather than try to handle them.They are mostly nocturnal and opportunistic carnivorous hunters, feeding on a broad variety of ground dwelling insects. Youngsters will eat crickets, or other small insects. Adults will consume almost any creature that is not larger that itself, including large crickets, other large insects, and even small lizards. Prefers out door environments but can be met with in urban areas .it is very beneficial in controlling pest species of other arthropods.

The House Centipide Scutigera coleoptrata Xini Ta`l-Indewwa is unfortunately a well considered pest locally. Originally endemic to the Mediterranean region, the species has spread to other parts of the world, where it usually lives in human homes. This species can live its entire life inside a building, usually the ground levels of homes. They are generally considered harmless to humans. Bites are not common, and the jaws of most house centipedes are not strong enough to penetrate human skin . the latter feed on spiders, bedbugs, termites, cockroaches, silverfish, ants, and other household arthropods. They administer venom through modified legs. These are not part of their mandibles, so strictly speaking they sting rather than bite. They are mostly nocturnal hunters. Despite their developed eyes they seem to rely mostly on their antennae when hunting. Their antennae are sensitive to both smells and tactile information. They use both their mandibles and their legs for holding prey. This way they can deal with several small insects at the same time. They avoid dangerous insects. They also adapted their feeding pattern to the hazard the prey might pose to them. For wasps, they retreat after applying the venom to give it time to take effect. When the centipede is in danger of becoming prey itself, it can detach any legs that have become trapped. They live anywhere from three to seven years, depending on the environment. They can start breeding in their third year. For mating the male and female circle around each other. They initiate contact with their antennae. The male deposits his sperm on the ground and the female then uses it to fertilize her eggs. Some report that the eggs are deposited in the ground and covered with plant matter. This species was observed providing parental care. The female lies on her side cradling her clutch of eggs, and later the larvae. This behavior was reported to proceed for several weeks. The female applies an antifungal secretion by mouthing the eggs. As its diet shows, it is a very beneficial species.


On the other hand most millipedes are slower than centipedes, and feed on leaf litter and detritus. They are distinguished by the fusion of each pair of body segments into a single unit, giving the appearance of having two pairs of legs per segment. Around 10,000 species have been described, which may represent less than a tenth of the true global millipede diversity .The name "millipede" is a compound word formed from the Latin roots milli ("thousand") and ped ("foot"). Despite their name, millipedes do not have 1,000 legs, although one rare species has up to 750. Common species have between 36 and 400 legs. Most millipedes eat decaying leaves and other dead plant matter, moisturising the food with secretions and then scraping it in with the jaws. However they can also be a minor garden pest, especially in greenhouses where they can cause severe damage to emergent seedlings. Signs of millipede damage include the stripping of the outer layers of a young plant stem and irregular damage to leaves and plant apices. Very few species are carnivores.

The millipede's most obvious feature is its large number of legs. Having very many short legs makes millipedes rather slow, but they are powerful burrowers. With their legs and body length moving in a wavelike pattern, they easily force their way underground head first. They also seem to have some engineering ability, reinforcing the tunnel by rearranging the particles around it. Their bodies have segmented sections which makes them move in a wave-like form.

The head of a millipede is typically rounded above and flattened below and bears large mandibles. The body is flattened or cylindrical, with a single chitinous( what their outer body is made of) plate above, one at each side, and two or three on the underside. In many millipedes, these plates are fused to varying degrees, sometimes forming a single cylindrical ring. The plates are typically hard, being impregnated with calcium salts

Unlike centipedes and other similar animals, each segment bears two pairs of legs, rather than just one. This is because each is actually formed by the fusion of two embryonic segments, and is therefore properly referred to as a "diplosegment," or double segment. The first few segments behind the head are not fused in this fashion, and the first segment is legless, while the second to fourth have one pair each. In some millipedes, the last few segments may also be legless. The head contains a pair of sensory organs known as the tomosvary organs. These are found just posterior and lateral to the antennae, and are shaped as small and oval rings at the base of the antennae. They are probably used to measure the humidity in the surroundings, and they may have some chemoreceptory abilities too. Millipede eyes consist of a number of simple flat lensed ocelli arranged in a group on the front/side of the head. Many species of millipedes, such as cave-dwelling millipedes, have secondarily lost their eyes.

Male millipedes can be differentiated from female millipedes by the presence of one or two pairs of legs modified into gonopods. These modified legs, which are usually on the seventh segment, are used to transfer sperm packets to the female during copulation. A few species are parthenogenetic, having few, if any, males.

Females lay between ten and three hundred eggs at a time, depending on species, fertilising them with the stored sperm as they do so. Many species simply deposit the eggs on moist soil or organic detritus, but some construct nests lined with dried faeces.

The young hatch after a few weeks, and typically have only three pairs of legs, followed by up to four legless segments. As they grow, they continually moult, adding further segments and legs as they do so. Some species moult within specially prepared chambers, which they may also use to wait out dry weather, and most species eat the shed exoskeleton after moulting. Millipedes live from one to more than ten years, depending on species.

Due to their lack of speed and their inability to bite or sting, millipedes' primary defense mechanism is to curl into a tight coil — protecting their delicate legs inside an armored body exterior. Many species also emit poisonous liquid secretions or hydrogen cyanide gas through microscopic pores along the sides of their bodies as a secondary defense. Some of these substances are caustic and can burn the exoskeleton of ants and other insect predators, and the skin and eyes of larger predators As far as humans are concerned, this chemical brew is fairly harmless, usually causing only minor effects on the skin, the main effect being discoloration.

Around 15 species of millipedes are known to occour locally. The most common home encounter is The Common Millipede Pachyiulus flavipes Hanex ta`L-Indewwa or Tad-Djar is found in most local establishments where high level of humidy persists. They can be handled, and are quite docile and slow moving. This species like most have two main modes of defense if they feel threatened: curling into a tight spiral exposing only the hard exoskeleton, and secretion of an irritating liquid from pores on their body.

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SCIBERRAS, A. (2013) Fauna regarded as domestic pests in the Maltese islands - The Hymenopteriods

The Hymenopteriods

By Arnold Sciberras

If you bug their house which is generally built on or under yours, they will sting you. If they don’t sting you, they will invade your property with their large numbers of individuals. Wasps, bees and ants (collectivly known as hymenopterods) are the creatures this article is dedicated for.

Hymenoptera is one of the largest orders of insects, comprising the sawflies, wasps, bees, and ants. There are over 130,000 species described with many others remaining to be. It is yet unknown how many species exist in the Maltese Islands as new species are found frequently but a very rough estimate from local literature indicates that till 1995 over 178 species comprising of 113 species of wasps, 46 species of bees and around 52 species of ants were already known locally. A number of these are endemic species such as the Maltese Slave Keeping Ant (Strongylognatus insularis) Nemlu ta’ Kemmuna, which is not only endemic to the Maltese archipelego but strictly to Comino Island.

Females typically have a special ovipositor for inserting eggs into hosts or otherwise inaccessible places. The ovipositor is often modified into a stinger. The young develop through complete metamorphosis — that is, they have a worm-like larval stage and an inactive pupal stage before they mature.

Hymenoptera vary from medium-sized insects to larger ones and usually have two pairs of wings. Their mouthparts are created for chewing, with well-developed mandibles. Many species have further developed the mouthparts into a lengthy proboscis (like butterflies), with which they can drink liquids, such as nectar. They have large compound eyes, and typically three ocelli.

In the more primitive hymenoptera, the ovipositor is bladelike, and has evolved for slicing plant tissues. In the majority, however, it is modified for piercing, and, in some cases, is several times the length of the body. In some species, the ovipositor has become modified as a stinger, and the eggs are laid from the base of the structure, rather than from the tip, which is in turn used to inject venom. The stinger is typically used to immobilise prey, but in some wasps and bees may be used in defence.

The larvae of most hymenoptera, however, closely resemble maggots, and are adapted to live in a protected environment. This may be the body of a host organism, or a cell in a nest, where the adults will care for the larvae. Such larvae have soft bodies with no limbs. They are also unable to defecate until they reach adulthood due to having an incomplete digestive tract, presumably to avoid contaminating their environment.

Among the hymenopterans, sex is determined by the number of chromosomes an individual possesses. Fertilized eggs get two sets of chromosomes and so develop into females, while unfertilized eggs only contain one set (from the mother), and so develop into males; the act of fertilization is under the voluntary control of the egg-laying female.

Different species of hymenoptera show a wide range of feeding habits. The most primitive forms are typically herbivorous, feeding on leaves or pine needles. Stinging wasps are predators, and will provide their larvae with immobilised prey, while bees feed on nectar and pollen.A number of species are parasitoid as larvae. The adults inject the eggs into a paralysed host, which they begin to consume after hatching.

True wasps, bees, and ants together make up the suborder Apocrita, characterized by a constriction between the first and second abdominal segments called a wasp-waist (petiole), also involving the fusion of the first abdominal segment to the thorax (second part of the body). Also, the larvae of all Apocrita look exactly like maggots.

The term wasp is typically defined as any insect of the suborder mentined above that is neither a bee nor ant [1]. Almost every pest insect species has at least one wasp species that preys upon it or parasitizes it, making wasps critically important in natural control of their numbers, or natural biocontrol. Parasitic wasps are increasingly used in agricultural pest control as they prey mostly on pest insects and have little impact on crops.The various species of wasps fall into one of two main categories: solitary wasps and social wasps. Adult solitary wasps generally live and operate alone, and most do not construct nests (below). All adult solitary wasps are fertile. By contrast, social wasps exist in colonies numbering up to several thousand strong organisms and they build nests – but in some cases not all of the colony can reproduce. In the more advanced species, just the wasp queen and male wasps can mate, whilst the majority of the colony is made up of sterile female workers.

Bees are flying insects closely related to wasps and ants, and are known for their role in pollination and for producing honey and beeswax. There are several different types of bees and in lame terms they are categorised as: (a) sting less bees; (b) honey bees; (c) solitary and communal bee; (d) cleptoparasitic bees and (e) nocturnal bees. Obviously not all caterogerios exists locally.

Ants are distinct from other insects in their appearance in having elbowed antennae, and a strong constriction of their second part of their abdomen. Many animals can learn behaviours by imitation but ants may be the only group apart from mammals where interactive teaching has been observed. A knowledgeable forager of a particular ant (Temnothorax albipennis) leads a naïve nest-mate to newly discovered food by the process of tandem running. The follower obtains knowledge through its leading tutor. Both leader and follower are acutely sensitive to the progress of their partner with the leader slowing down when the follower lags, and speeding up when the follower gets too close.

Although many species are regarded as domestic pests, nearly none have proved to be an actual pest (e.g. carrying disease, etc) but their persistance in numbers is genrally regarded as a niusance to the owner of the establishment.

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SCIBERRAS, A. (2013) Fauna regarded as domestic pests in the Maltese islands - The Fleas

The Fleas
By Arnold Sciberras

As if a long day at work isn’t enough. You arrive home and immediately try to relax a bit on the couch. The areas where your socks end on your legs start itching. You quickly realize you are not alone….you are accompanied by a creature this article is dedicated for.

‘Flea’ is the common name for insects of the order Siphonaptera which are wingless insects with mouthparts adapted for piercing skin and sucking blood. Fleas are external parasites, living on the blood of mammals (including humans) and birds. In the past, it was most commonly thought that fleas had evolved from the flies (Diptera), based on similarities of the larvae. Now it is more certain that they are descendants of the Scorpionfly family Boreidae, which are also flightless. There are around 2000 species of fleas known worldwide and the number of local species is yet to be determined.

Fleas are small, agile, usually dark coloured (for example, the reddish-brown cat flea), wingless insects with tube-like mouth-parts adapted to feeding on the blood of their hosts. Their legs are long, the hind pair well adapted for jumping vertically up to 18 cm and horizontally up to 33 cm. This is around 200 times their own body length, making the flea one of the best jumpers of all known animals (in comparison to body size), second only to the froghopper. Their bodies are laterally compressed, permitting easy movement through the hairs or feathers on the host's body (or in the case of humans, under clothing). The flea body is hard, polished, and covered with many hairs and short spines directed backwards, which also assist its movements on the host. The tough body is able to withstand great pressure, likely an adaptation to survive attempts to eliminate them by such as mashing and scratching. Even hard squeezing between the fingers is normally insufficient to kill a flea.

Fleas are insects that carry out complete metamorphosis, which consists of four stages: egg, larva, pupa and adult. The flea life cycle begins when the female lays the eggs after feeding. Adult fleas must feed on blood before they can become capable of reproduction. Eggs are laid in batches of up to 20 or so, usually on the host itself, which easily roll onto the ground. As such, areas where the host rests and sleeps become one of the primary habitats of eggs and developing fleas. Fleas lay tiny white oval shaped eggs better viewed through a loupe. The eggs take around two days to two weeks to hatch. They are blind and avoid sunlight, keeping to dark places like sand, cracks and crevices, and bedding. The larva is small, pale, has bristles covering its worm-like body, lacks eyes, and has mouthparts adapted to chewing. The larvae feed on organic matter, especially the feces of mature fleas, but also feed on dead insects and vegetable matter.

Given an adequate supply of food, larvae should pupate and weave a silken cocoon within 1–2 weeks after 3 larval stages. After another week or two, the adult flea is fully developed and ready to emerge from the cocoon. They may however remain resting during this period until they receive a signal that a host is near - vibrations (including sound), heat, and carbon dioxide are all stimuli indicating the probable presence of a host. Fleas are known to overwinter in the larval or pupae stages.

Once the flea reaches adulthood its primary goal is to find blood as it is the only diet for adult fleas. Adult fleas only have around a week to find food once they emerge, though they can survive two months to a year between meals. As previously mentioned, adult fleas must feed in order to reproduce. A flea population is unevenly distributed, with 50 percent eggs, 35 percent larvae, 10 percent pupae, and 5 percent adults. Their total life cycle can take as little as two weeks, but may be lengthened to many months if conditions are favorable. Female fleas can lay 500 or more eggs over their life. Adaptation can be clearly observed in Rabbit Fleas (Spilopsyllus cuniculi) Bergħud tal-Fniek. Adult females of this species can detect the changing levels of cortisol and corticosterone, hormones in the rabbit's blood that indicate she is getting close to giving birth. This triggers sexual maturity in the fleas and they start producing eggs. As soon as the baby rabbits are born, the fleas make their way down to them and once on board they start feeding, mating, and laying eggs. After 12 days, the adult fleas make their way back to the mother. They complete this mini-migration every time she gives birth.

Fleas attack a wide variety of warm-blooded vertebrates including dogs, cats, mice, chickens, rabbits, squirrels, rats, ferrets, and humans. The most common species include Cat Flea (Ctenocephalides felis) Bergħud tal-Qtates. The primary host of this species is the domestic cat, but this is also the primary flea infesting dogs in most of the world. The cat flea can also maintain its life cycle on rabbits, rodents, ruminants and humans can be infested or bitten, but a population of cat fleas cannot be sustained by these aberrant hosts. The Dog Flea (Ctenocephalides canis) Bergħud tal-Klieb, is very similar in habit to the cat flea but it is more commonly found in Europe. On the other hand, the Human Flea (Pulex irritans) Bergħud tal-Bniedem, is a cosmopolitan flea species that has, in spite of the common name, a wide host spectrum.

Fleas are a nuisance to their hosts, causing an itching sensation which in turn may result in the host attempting to remove the pest by biting, pecking, scratching, etc the vicinity of the parasite. Fleas are not simply a source of annoyance. Some people and animals suffer allergic reactions to flea saliva resulting in rashes. Flea bites generally result in the formation of a slightly-raised swollen itching spot with a single puncture point at the center (similar to a mosquito sting). The bites often appear in clusters or lines of two bites, and can remain itchy and inflamed for up to several weeks afterwards. Fleas can also lead to hair loss as a result of frequent scratching and biting by the animal, and can cause anemia in extreme cases. Besides the problems posed by the creature itself, fleas can also act as a vector for disease. A very famous example is the Black Death, which killed millions of people in Europe because of a flea species which was common on Black Rats, which acted as a vector for the bacterium Yersinia pestis. Fleas that specialize as parasites on specific mammals may use other mammals as hosts; humans are therefore susceptible to the predation of more than one species of flea.



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