LALAT LULI

introduction

True flies are insects of the order Diptera (from the Greek di = two, and Patera = wings). The most obvious distinction from other orders of insects is that a typical fly possesses a pair of flight wings on the mesothorax and a pair of halteres, derived from the hind wings, on the metathorax. (Some species of flies are exceptional in that they are secondarily flightless). The only other order of insects bearing two true, functional wings plus any form of halteres are the Strepsiptera, and in contrast to the flies, the Strepsiptera bear their halteres on the mesothorax and their flight wings on the metathorax.
Same like mosquitoes, class Insecta and have complete metamorphosis. Larval stage known as maggot. When eggs laid in the flesh of mammals, resulting larvae invade surrounding living tissue, resulting condition known as Myasis . Flies as carriers of disease-causing agents and destroyers of food.  Also can be classified as biting flies (sand flies, horseflies, deerflies) or nonbiting flies (houseflies, bottleflies, screw worm flies).  Latter know as synanthropic flies, referring to their close association with humans.

MORPHOLOGY OF FLIES

The adults of Diptera are fairly uniform in the general morphology and do not show strong differences, within the order, about the basic morphological regions. For example, a general description of Hemiptera, inevitably falls into considerable differences between the females of scales and a pentatomiid, because they are very different organisms. Almost all adults of Diptera are basically similar, despite the differential growth of individual regions, that gives differences in the global appearance. For example, although they appear very different, a Housefly and a mosquito are united by evidence of a head, thorax, abdomen, three pairs of legs, a pair of wings, a pair of antennae, etc. This lacks substantial convergence when one examines the details of morphology, such as the structure and the features of the mouthparts or the Terminalia.

The body of Diptera have the usual heteronomous metamerism of many insects, with the subdivision into three main morphological regions: head, thorax, and abdomen. These regions bear some articulated appendages, also present in most insects:

a pair of antennae;
the complex of mouthparts, composed by the labrum, two pairs of symmetrical appendages and two median appendages. These appendages are strongly modified, compared to the structure of typical chewing mouthparts, and some of them may be vestigial or completely absent. The mouthpart of Diptera is structured to allow, through different mechanisms, the assumption of liquid food; sometimes the mouthparts also have the piercing functionality;
two pairs of wings. The front ones are well developed, the hind are transformed in halteres. Brachyptery, microptery, and aptery are very rare;
three pairs of legs, as cursorial or ambulatorial in most of order. Sometimes some raptorial legs are adapted to saltatorial or functionality;
the complex of Terminalia, that is very complicated in the males. These appendages contribute to form an apparatus composed also by the strong modification of last abdominal segments. In females, the gonapophyses usually present in semen insects, are reduced or absent and their function is subrogated by a modification of last segments;
a pair of cerci, generally reduced compared with cerci present in more primitive orders.
Except for some wingless forms, which require more detailed examination, most Dipters are easily recognizable by the presence of only the mesothoracic wings, a pair of halteres, and mouthparts forming a proboscis able to suck or lick fluids. There are few insects that have characters that may confuse them with flies. Presence of only two wings occurs only in Ephemeroptera order, in males of Strepsiptera, and in males of scales (Hemiptera: Coccoidea). The Mayfly are easily distinguished by the absence of halteres and the presence of long cerci. The males of Strepsiptera are distinguished by the different position of wing and halteres: the hind wings are normally developed, while the mesothoracic wings are reduced to halteres, so they are placed before of wings. Yhe males of the Cochineal, like Dipters, have mesothoracic metathoracic wings and halteres, so require a closer examination. They can be distinguished by the different morphology of mouthparts and the presence, in general, of long caudal appendages.

FLIES CYCLE

The Housefly life cycle closely mirrors that of most insects: a basic cycle that begins with an egg, larva then develops through a phase, a pupa phase, and finally, into an adult. During a warm summer - optimal conditions for a Housefly - the cycle, from fertilized egg to adult, spans a mere seven to 10 days.

After a Housefly male chases down and fertilizes a female counterpart, she's ready to lay her eggs. Houseflies are solitary creatures. Like the rest of the insect world, males and females do not stick together after mating and, unlike nesting insects, females do not care for or protect eggs. Females simply leave the eggs where they will be safe from predators and have plenty to eat upon hatching.

The female deposits her eggs Housefly in the crevices and corners of the same kinds of decaying organic matter adults feed on. Within a day, the first larvae begin to emerge from the eggs. Also known as maggots, these worm-like creatures are little more than fleshy, sectionless tubes with hooked mouth parts used for feeding.

The maggots grow rapidly. In less than two days they've doubled in size and therefore must molt. Molting is a process common to many invertebrates through which a growing insect sheds its exoskeleton and former grows a new one. A maggot will molt twice more, larger and more developed emerging each time.

Following its third molt, larvae will burrow deep into the substance they've been feeding on. Their skins will darken and harden as they enter the pupa stage. Inside this protective shell, the larva will fully develop the body segments and appendages of an adult Housefly.

The only visible addition to the emerging Housefly is a swollen bump on the fly's head, used to break through the shell. Since the Housefly does not have teeth or jaws to chew its way out, it uses this fluid-filled pouch to break through the shell pupae. Once fully emerged, the bump deflates back into the fly's head.

A new adult Housefly has, at most, three months to reproduce before it dies. With so many predators, a Housefly's average lifespan is even shorter: 21 days. Luckily for the Housefly, the phrase "breeding like flies" is not just a figure of speech. Each female can lay up to 900 eggs during her brief life.

The very thought of a Housefly infestation may prove too disturbing for many homeowners. However, the next page will describe how a manageable amount of houseflies helps regulate the local ecosystem.

Family Muscidae 

Identification Small to rather large flies, often resembling house flies. Second antennal segment cleft; vein Cu₁ + 1A not reaching margin of wing; lower calypterae nearly always longer than upper one; prosternum sclerotized.

Includes the genera Stomoxys, Lyperosia and Haematobia in which both sexes feed on mammalian blood. Also many other genera which do not feed on blood such as Musca, although some feed on body secretions. The larvae of most species are saprophagous, whilst some are carnivorous.

Stomoxys calcitrans (Stable fly)

Identification & Distribution: Body length 4-7 mm; mouthparts extended forwards as a long piercing proboscis; palps less than one third the length of the proboscis; gray in colour with four black stripes on the thorax; characteristic pattern of dark spots on the second and third abdominal segments - one marked median spot and two lateral round spots. Distributed worldwide having been introduced to North America in the 1700s.

Biology & Disease Transmission: Important biting insect pests of livestock especially cattle and horses, but will feed on a wide range of vertebrate hosts including man, birds and reptiles. Main harm is through disturbance of feeding, but may also be a disease vector especially of mastitis in dairy cattle herds.

   

These are two female Stomoxys calcitrans, the first sunbasking near cattle and the second having inadvertently flown into a house in Dorset. Note the long piercing proboscis and the pattern of dark spots on the abdomen. Stable flies are important pests of cattle and numbers present in an area are commonly monitored with sticky panels.

This shows the catch - here a mixture of tsetse flies (Glossina austeni) and Stomoxys - being removed from a sticky panel used to sample biting flies in Bodhai in the Garissa district of Kenya.Beresford & Sutcliffe (2008)  working on a dairy farm in Canada have demonstrated the critical importance of the height of the sticky trap above the vegetation in determining catch size.

Musca autumnalis (Face fly)

Identification & Distribution: Both sexes have red eyes, a grey thorax with four black stripes and wings tinted orange towards the base. Abdomen more rounded than Musca domestica. Male has black abdomen with bright orange patch on each side; female is has a grey and black checkerboard of patches. Distributed through most of Europe, central Asia through to north India and China and parts of North Africa; introduced to North America in the 1940s.

Biology & Disease Transmission: Very common around cattle and horses. Larvae develop in cow pats; adults feed on secretions from eyes and nose of cattle and horses and occasionally on blood exuding from horse fly bites. As well as disturbance to feeding (especially to horses), face flies can transmit the eyeworm Thelazia rhodesi to cattle and horses, and the bacterium Moraxella bovis, which causes infectious bovine keratoconjunctivitis ('pink eye') in cattle. Also implicated as a vector of the bacterium Corynebacterium pyogenes which causes mastitis.

   

The first image shows a male and the second a female. Both were sun basking on a fence in a group of about ten flies. Such aggregations are not uncommon with this species and presumably facilitate mating.

   

The images show faceflies and other muscids feeding on secretions from the eyes and nose of cattle. Various methods of insecticidal control have been used, but they are all only partially effective (Thomas & Jesperson, 1994 ).

Musca domestica (House fly)

Identification & Distribution: Both sexes have red eyes, a grey thorax with four narrow black stripes, a sharp upward bend in the fourth longitudinal wing vein, and a pointed elongate abdomen (relative to Musca autumnaria). Male has a yellowish abdomen with dark dark midline and some irregular dark markings on the sides; female has a grey and black checkerboard of patches. Distributed worldwide.

Biology & Disease Transmission: Usually found in close association with humans or human activities. Feeds and oviposits on decomposing and rotting organic matter and settles on humans, their food and utensils. A common pest of pig and poultry farms as well as horse stables and cattle barns. Has the potential to distribute hundreds of different pathogenic organisms and known to transmit many of them including Salmonella, Shigella and Campylobacter. Most commonly linked to outbreaks of diarrhoea and shigellosis, but also other diseases such as typhoid fever and anthrax. Houseflies also carry the eggs and cysts of many intestinal worms, including Ascaris spp., hookworms and tapeworms.

This image shows a male house fly sitting on the work surface in a kitchen. The main method of fly control is good sanitation, but insecticides and traps may also be useful.

Table 1. 

Descriptions of filth-breeding flies.

Pests	Description	Breeding Habits	Life Cycle	Control
				Non-Chemical	Chemical
House Fly	About 1/4" in length; dull gray; thorax marked longitudinally with 4 dark stripes; abdomen pale and fourth wing vein is angled.	Warm organic material such as animal and poultry manure, garbage, decaying vegetables and fruits and in piles of moist leaves and lawn clippings.	6 to 10 days	Sanitation and destruction of breeding sites; tight fitting garbage containers and screens on windows and doors.	Larvicides; residual and space sprays; baits.
Green Bottle Fly	About 1/2" in length with shiny metallic blue-green abdomen and thorax.	Dead animal carcasses, decomposing meat and fish, garbage, and sometimes animal excrement.	9 to 21 days	Sanitation and destruction of breeding sites; tight fitting garbage containers and screens on windows and doors.	Larvicides; residual and space sprays.
Bronze Bottle Fly	About 1/2" in length with a shiny bronze abdomen and thorax.	Dead animal carcasses, decomposing meat and fish, garbage and sometimes animal excrement.	9 to 10 days	Sanitation and destruction of breeding sites; tight fitting garbage containers.	Larvicides; residual and space sprays.
Blue Bottle Fly	About 1/2" in length with a dull thorax and shiny blue abdomen.	Dead animal carcasses, decomposing meat and fish, garbage, over-ripe fruit, decaying vegetable matter and sores on living humans.	15 to 20 days	Sanitation and destruction of breeding sites; tight fitting garbage containers and screens on windows and doors.	Larvicides; residual and space sprays.
Moth Flies or Filter Flies	1/16" to 1/8" in length; light gray to tan.	Decomposing organic material such as moist plant litter, garbage, sewage, around kitchen or bathroom sinks and water traps in plumbing fixtures.	7 to 20 days	Sanitation and destruction of breeding sites, tight fitting garbage containers and moisture control.	Larvicides; residual and space sprays.
Eye Gnats	About 1/16" in length, shiny black to dull gray with yellow or orange markings on the legs and have small mouthparts and bare aristae on antennae.	Loose soil containing considerable organic material, decaying vegetation and animal excrement.	7 to 28 days	Sanitation and destruction of breeding sites.	Repellents; residual and space sprays.
Humpbacked Flies	About 1/8" in length with a small head and large thorax causing the fly to have a hump-backed appearance.	Decaying vegetation, animal debris, garbage and in ant and termite nests.	10 to 25 days	Sanitation, destruction of breeding sites and moisture control.	Residual and space sprays.
Blind Mosquitoes	3/16" to 1/2" in length with a slender body, large thorax, small head, and slender, 5- to 14-segmented antennae.	Lakes, ponds, rivers, streams, reservoirs, and tanks.	8 to 21 days	Moisture Control	No suitable control.
Black Blow Flies	About 1/3" in length with a shiny metallic dark blue abdomen and thorax.	Dead animal carcasses, garbage, and wounds in living animals.	8 to 10 days	Sanitation and destruction of breeding sites; tight fitting garbage containers.	Larvicides; residual and space sprays.
Flesh Flies	3/8" to 9/16" in length, dull grayish-black with three dark stripes on the thorax.	Decayed flesh and spoiling meat, manure, wounds in living animals, and sometimes garbage.	8 to 21 days	Sanitation and destruction of breeding sites.	Residual and space sprays.
Vinegar Flies	About 1/8" in length, brownish-black to brownish-yellow and have a feathery bristle on the antennae.	Fermenting or rotting fruit and vegetable material and in garbage cans.		Sanitation and destruction of breeding sites; tight fitting garbage containers.	Residual and space sprays.
Dump Flies	About 1/4" long, black with a shiny thorax and abdomen.	Garbage and fowl excrement. The larvae are predaceous on larvae of other flies.		Sanitation and destruction of breeding sites.	Larvicides; residual and space sprays.
Secondary Screwworm Flies	About 1/4" long, green, shiny abdomen and thorax with thorax marked lengthwise with 3 dark stripes.	Dead tissue surrounding wounds in animals, fresh cut meats, and garbage.	9 to 39 days	Sanitation and destruction of breeding sites.	Residual and space sprays.

MODE OF TRANSMISSION

On their mouthparts
•Through their vomitus
•On their body and leg hairs
•On the sticky pads of their feet
•Through intestinal tract by means of fly feces.


MYIASIS

Myiasis is the parasitic infestation of the body of a live mammal by fly larvae (maggots) that grow inside the host while feeding on its tissue. Although flies are most commonly attracted to open wounds and urine- or feces-soaked fur, some species (including the most common myiatic flies, the botfly, blowfly and screwfly) can create an infestation even on unbroken skin and have even been known to use moist soil and non-myiatic flies (such as the common housefly) as vector agents for their parasitic larvae.

Colloquialisms for myiasis include flystrike and blowfly strike, and the victim or the tissue may be described as fly-blown. The name of the condition derives from ancient Greek μυῖα (myia), meaning "fly".

Because some animals (particularly domestic animals) cannot react as effectively as humans to the causes and effects of myiasis, such infestations present a severe and continuing problem for livestock industries worldwide, causing severe economic losses where they are not mitigated by human action. Although typically a far greater issue for animals, myiasis is also a relatively frequent affliction of humans in rural tropical regions where myiatic flies thrive, and often may require medical attention to surgically remove the parasites.

Myiasis varies widely in the forms it takes and its effects on the victims. Such variations depend largely on the fly species and where the larvae are located. Some flies lay eggs in open wounds, other larvae may invade unbroken skin or enter the body through the nose or ears, and still others may be swallowed if the eggs are deposited on the lips or on food.