Pests from A to Z
Flies
A family of two-winged polluters that is, too often, tolerated within our homes.
Apart from the biting flies, all species feed by vomiting saliva on to the food surface, and sucking up the resulting liquid. In the course of doing so, the fly contaminates the food with bacteria from its gut and its feet. Thus, it may transmit food poisoning, dysentery, typhoid or cholera in countries where these occur.
The eggs of parasitic worms may also be carried by flies.
Blow Fly
Blow flies are so called because they were believed to “blow” their eggs, or larvae on to exposed meats. It is a general description of a number of species of large buzzing flies, which include the Bluebottle, the Greenbottle and the Flesh Fly. They all like sunlight and are attracted to meat or carrion, and all may be found around dustbins in hot summer weather.
Their feeding habits (they vomit onto food to soften it up) and filthy feet, infect food, especially meat products, as they feed or seek egg-laying sites. Their Latin names indicate their habits; Calliphora vomitoria, Sarcophaga carnaria and Cyanomyia cadaverina are but three members of the group with a great capacity for transmitting the bacterial agents of food poisoning.”
Bluebottle
The Bluebottle is a large buzzing fly with shiny, metallic blue body, 6-12mm long.
One Bluebottle can lay up to 600 eggs, which in warm weather will hatch in under 48 hours and produce maggots which can become fully developed in a week. These maggots burrow into meat or carrion as they feed on it, and then pupate, often in loose soil, for about ten days before emerging as adult flies from the brown pupal case.
Bluebottles, like other flies, are often found around refuse tips, rotting animal matter, dirt and dustbins. They commute from filth to food, and carry bacteria on their legs, feet and bodies.
Cheese Skipper
A small shiny black fly with reddish eyes whose slender grubs “skip” by curving their body into a ring and releasing themselves. The larvae burrow into cheese or ham and can cause internal irritation if eaten.
Cluster Flies
These are dark greyish flies about 8mm long with yellowish hairs on the back and with overlapping wings. In autumn they congregate in large numbers in upper rooms or roof spaces of houses to hibernate. A mass of cluster flies has a characteristic smell. They are sluggish in flight and are a nuisance in the house.
The larvae of one species are parasitic upon certain earthworms, so this species is more common in rural areas.
Crane Fly
The familiar Daddy-Longlegs. A large mosquito-like fly with a long narrow body, which enters buildings in late summer. Harmless, although unpleasant in appearance. Its larva is the “leather- jacket” which damages grass roots.
Fruit Flies
A family of very small (about 3mm) flies, some with prominent red eyes, characterised by a slow hovering flight in which the abdomen hangs down. All are associated with rotting fruit and vegetables or fermenting liquids. One species breeds in sour milk, for example, in the residue of forgotten milk bottles.
Gnats
The insect normally referred to as a gnat is actually a small mosquito – correct name: Culex pipiens. It is common in gardens on warm evenings. Another species, the true Window Gnat, is a slow-flying insect about 8mm long with wings more rounded than those of the mosquito.
The wings are strongly veined with dark tips. Eggs of the Window Gnat are laid on rotting fruit or vegetables or other moist food and the larvae may contaminate home-made wines or honeycombs.
It is one of several species known as “filter flies” which breed in sewage filters; so homes near to sewage works may be invaded by them.
Green Bottles
Large buzzing flies about 9mm long with a characteristic bottle-green sheen on the back. Mostly carrion feeders that enter houses to seek places to hibernate and, in passing, may well alight on exposed foodstuffs.
House Fly
The Common Housefly and the Lesser Housefly are the most widespread household flies. The adult is 7-8mm long, grey in colour with black stripes on the back, with a single pair of veined membraneous wings.
The large compound eyes take up most of the head and are wider apart in the female than the male of the species. The smaller Lesser Housefly, rejoicing in the scientific name Fannia canicularis, is the one that cruises around light fittings, abruptly changing direction in mid-flight. The Housefly has a sticky pad on each of its six hairy feet, and these enable it to walk upside down on ceilings or crawl up windows.
Houseflies complete their life cycle of egg, maggot, pupa, adult in a week during warm weather. The eggs are laid in batches of about 120 on rotting organic matter and the legless white maggots burrow into this food until ready to pupate in loose soil or rubbish.
The answer to “where do flies go in the winter?” is that some hibernate, but most pass the winter in the pupal stage. Houseflies may transmit a wide range of bacterial diseases.
Lacewing
The pale green Lacewing is a harmless wanderer from the garden or woods where its larvae prey upon other insects.
It has a pale green, soft body, about 15mm long, with richly veined transparent wings folded over it when at rest. The eyes are an iridescent bronze. The adults are attracted to light and may enter houses in autumn seeking hibernation sites.
Treatment is not necessary.
Lesser Housefly
See Housefly
Maggot
The layman’s term for the legless, wriggling larval stage of certain insects – usually the larvae of flies
Midges
Tiny dark grey flies, only about 2mm long with hair-fringed wings, most prevalent in spring and summer near sewage works. Also known as Filter Flies or Owl Midges, their grubs perform a useful purpose because they break down organic material at sewage works.
Sewage Flies
See Gnats
Stable Fly
Closely resembles the Housefly, but this fellow bites. Uncommon indoors but breeds in long grass, straw or grass cuttings where there are horses or other animals.
Thrips
Also known as “thunder-flies”, very small (1.5mm) insects, black with narrow hairy wings. They feed on plant sap and on humid summer days they may occur in huge numbers on window sills and getting into clothing and hair.
An agricultural pest, they are only a nuisance in domestic premises. They have been known to trigger fire alarms by collecting in large numbers inside smoke detectors.
Yellow Swarming Fly
One of the species collectively known as Cluster Fly family. A small yellowish fly with black stripes on its back which sometimes invades attics or rarely-used rooms to hibernate in autumn.
