Fly Information

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Phylum, Arthropoda; Class, Insecta; Order, Diptera

Identifying Features

Appearance (Morphology)

  • Three body parts: head, thorax, abdomen
  • One pair of fully developed wings
  • Hind wings are reduced to halteres (small knob-like structures) used to maintain equilibrium.
  • Adult mouth parts are sponging, lapping, or piercing
  • All adults look like flies, but some may have a metallic color (blue bottle fly).
  • Antennae may be difficult to see.

Adult Males and Females
Males and females are hard to distinguish. Females are usually larger and can extend the tip of the abdomen to form an ovipositor which is used to lay eggs. Sometimes males have enlarged eyes which meet on top of the head.

Immatures (different stages)
Flies are holometabolous, therefore they have four distinct morphological stages; egg, larva (maggot), pupa and adult. After hatching from the egg, larvae molt twice as they grow. Molting of maggots is difficult to see. Larvae are maggots with a legless soft body except for the dark mouth hooks. Pupae are dark, and look like a small barrel.

Natural History

Larvae feed on decaying meat and feces. Adult flies feed on sugary food of any kind, including nectar and rotting fruit.

Flies live in garbage and wherever animal feces are available. Dead animals attract flies within hours after death. Most flies are diurnal.

Many birds, bats, spiders, and insects such as dragonflies eat the adults. Predatory and parasitic insects eat the larvae.

Interesting Behaviors

  • The eyes of flies are among the most complex in the insect world. They are compound eyes with many individual facets, each representing a separate light-detecting unit. The light reflected from the eye of a horsefly can form a rainbow.
  • Flies taste, smell, and feel with the hairs that cover their bodies. The hairs on the fly's mouth parts and feet are used for tasting. Flies taste what they walk on. If they walk onto something tasty, they put down their mouth and taste it again.
  • Flies use other hairs to tell them when they touch something. These hairs bend when touched.
  • The eyes of a fly do not have eyelids, so flies rub their eyes with their feet to keep them clean.
  • A fly cleans itself constantly.
  • Flies walk on smooth surfaces using sticky soft pads that act like glue. This allows them to walk on vertical glass surfaces and upside down.

Impact on the Ecosystem

Flies and other insects, such as burying beetles, are very important in consuming and eliminating dead bodies of animals. Flies are also essential in the conversion of feces and decaying vegetation to soil. Flies serve as prey to many other animals. Some flies aid in pollination.

Because of their habits of being attracted to feces and decaying meat, flies have been implicated in transmission of disease such as dysentery, typhoid fever, and cholera.

Collecting Live Insects

Where to find
Flies live around rotting food, decaying meat and animal feces. Horse stables, feed lots and restaurant trash bins are a few of the fly-frequented areas. Flies are more common in warm weather.

How to collect
Placing the fly trap in these areas should be successful. If there are many flies flying around a certain area, use an insect net. Quickly move the net back and forth in the area (i.e., outside a trash bin). With each motion the flies go to the bottom of the net. When you stop moving the net, quickly close the top of the net so that flies do not escape. If you catch flies with a net, place them in the fly trap for observation activities.

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Center for Insect Science Education Outreach The University of Arizona
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