Structure Invading Flies
Appearance / Identification
A typical adult fly has three body parts: head, thorax and abdomen. The colour and body size varies depending on species; most are small in size, typically measuring no more than 10 millimetres long. The head has a pair of compound eyes, a pair of antennae, and variously modified mouthparts. The thorax is the locomotor center; it bears a pair of functional membranous wings used in flight and three pairs of functional legs. The immature forms, called larvae, are tiny, cream-whitish, legless, and often worm-like.
Because of their sheer abundance and varied habitats, flies frequently come in contact with humans and some have the ability to transmit disease-causing germs. More than 100 pathogens are associated with the house fly including: Salmonella, Staphylococcus, E. coli and Shigella. These pathogens can cause disease in humans and animals, including: typhoid fever, cholera, bacillary dysentery, hepatitis, ophthalmia, polio, tuberculosis and infantile diarrhea. Sanitation is critical to controlling these pests, but accurate identification is essential for successful fly control. Some of the most common fly species of concern in Canada include blow flies, cluster flies, drain flies, fruit flies, and house flies.
Here are some other facts you should know about flies and fly control:
- Depending on the species, the life expectancy of a fly is eight days to two months, or in some cases, up to a year.
- Flies belong to the Order Diptera, meaning two wings. There are 16,000 species of flies in North America.
- Flies plague every part of the world except the polar ice caps.
- One pair of flies can produce more than 1 million offspring in as little as six to eight weeks.
- As many as 33 million microorganisms may flourish in a single fly’s gut, while a half-billion more swarm over its body and legs.
- Flies spread diseases readily because they move quickly from rotting, disease-laden garbage to exposed exposed human foods and utensils.
- Because they only have two wings, flies land often and therefore can deposit thousands of bacteria each time they land.
- U.S. Department of Agriculture sources reveal that flies contaminate or destroy $10 billion worth of agricultural products.
- For every fly seen, there are an estimated 19 more hidden from view. This means humans don’t even see most of the flies present at an infestation.
True Flies vs Flies as Pests
Though some flying insects are often referred to as flies, they are not true flies. True flies belong to the insect order Diptera which are characterized by two functional membranous wings and a second pair of wings modified into halters, structures used for braking while flying. True flies are one of the most prolific and successful categories of insects in the world, with roughly 17, 000 species found in North America alone. They are highly adaptable to various environments and so are able to survive in a wide range of environments and gain sustenance from a variety of different food sources.
Flies generally live within close proximity to suitable food sources and breeding grounds. They feed on various food substances; however, most of the flies found in and around buildings feed and breed in warm, moist decaying organic matter. Small flies such as drain flies, fungus gnats, and phorid flies are commonly found in and around drains, leakages in slab floors, shower pans, sinks, and overwatered potted plant soils. Fruit flies tend to breed in decaying fruits and vegetables. Meanwhile, filthy flies such as house flies, dung flies, blow flies, bottle flies, and flesh flies visit and breed in garbage, trash bins, piles of compost or manure, and the carcasses of animals. Flies are attracted to light, so they often gather around windows when inhabiting indoor areas. Some fly species such as blow and bottle flies are known to fly long distances of up 20 miles in search of food and breeding sites.
Flies undergo complete metamorphosis consisting of egg, larva, pupa and adult stages. Sexual mature female flies lay eggs on suitable material; the number of eggs laid depends on the fly species. The eggs hatch into tiny, whitish, legless larvae also known as maggots that resemble tiny worms. After completing the larval stage of development, the larvae become pupae from which the adults develop. The development time from egg to adulthood depends on the temperature of the surrounding environment. Colder temperatures prolong the life cycle, while warmer temperatures shorten it. In general, flies complete the life cycle within a few weeks and live an additional few weeks or months as adults.
Example of fly larva pictured for identification purposes