Wikijunior:Bugs/Fly

The word "fly" is often used to describe the house fly. There are more than 110,000 species of flies. That makes the Fly group the fourth largest insect group.

What does it look like?

A house fly on the wall

House flies are the best known fly species. Like all insects, they have 6 legs, 2 antenna, and 3 body regions (head, thorax, and abdomen). Antenna bristles are slightly feathery.

Most house flies are 1/16-inch to 1/2-inch long. They are dark with 4 black, lengthwise stripes on the thorax (middle section). Instead of chewing mouthparts, they have sponging mouthparts. They have reddish eyes.

Their long, hairy legs have adhesive pads and sharp claws on the tarsus (last segment). They have wings only on the thorax. Wings are made of thin sheets of chitin sandwiched together. A network of veins runs between the sheets to give support. The wings are held level and straight over the back.

Where does it live?

House flies occur worldwide except in Antarctica and a few remote islands.

They are commonly found on poultry and hog farms, horse stables and ranches. They are found where there is waste for food and manure for breeding.

What does it eat?

Adult house flies feed where they find decaying matter, sugar, or flower nectar. They feed on honeydew left by aphids or other bugs. Adult houseflies never have chewing mouthparts. They use saliva to change solids to liquids. Sponge-like mouthparts pick up semi-liquid foods, such as feces and decaying matter.

Fly larvae feed on moist organic matter. They need to store away a great deal of protein so as adults they have energy to search for food, find a mate, and produce eggs. They have sharp, curved “mouth hooks” used to scrape and cut solid food before flooding it with digestive enzymes.

How does it defend itself?

The fly's main defenses are its speed and agility. It has eyes that can see a very wide view of the world and help them notice fast movement and escape predators. Flies are often preyed upon by birds, spiders, and other flying insects.

What stages of metamorphosis does it go through?

House flies and their larvae (maggots) breed most commonly in manure. They undergo complete metamorphosis with egg, larval, pupal, and adult stages.

Female house flies lay 5 to 6 batches of 75-120 white oval eggs. Larvae hatch from eggs in about 12 hours. They are segmented, tapered at the head and blunt at the end. After growing for about 5 days they change into rounded, oblong pupae. Mature adult flies emerge after about 5 more days.

They begin breeding almost immediately. Thus, each new generation takes 10 to 12 days to develop. If temperatures are low, development may take a month or longer. Males live about fifteen days. Females live up to twenty-six days if they have access to food and water.

If a single female house fly laid 120 eggs in spring, and if all offspring survived, over five-trillion new flies could hatch by fall!

What special behavior does it exhibit?

House flies are “disease vectors,” carrying as many as a half billion bacteria and other organisms on their body at one time.

Adult house flies can taste with their feet! They use a “vomit drop” of saliva to turn solid morsels into liquid nourishment.

If there are clear plastic bags, half-full of water, outside doors and windows, house flies have trouble. The constant motion of the water interferes with their vision.

How does this bug affect people?

House flies carry germs that cause dysentery, anthrax, typhoid fever and other diseases. They breed in unclean places. Their soft, sticky feet and hairy legs pick up “filth” from contaminated matter. When they land on people or objects, they drop bacteria and germs with every step.

House flies can be beneficial to people as pollinators of flowering plants and decomposers of waste matter.

References

Anderson, R. (1988). Guide to Florida Insects. Erwin Lampert Publishing.

Eaton, E. R. and Kaufman, K. (2007). Kaufman field guide to insects of North America. New York, NY: Houghton Mifflin Company.

Marshall, S. A. (2006). Insects their natural history and diversity. Richmond Hill, Ont.: Firefly Books Ltd.

McGavin, G. C. (2000). Dorling Kindersley handbooks Insects spiders and other terrestrial arthropods. New York, NY: Dorling Kindersley, Inc.

Milne, L. & Milne, M. (2000). National Audubon Society field guide to insects and spiders. New York, NY: Alfred A. Knopf, Inc.

Shea, G. & Bickel, D. (Eds.). (2004). Encyclopedia of discovery, reptiles and insects. San Francisco, CA: Fog City Press.

Waldbauer, Gilbert (2003). What good are bugs? Insects in the web of life. Cambridge, MA: Harvard University Press.