Life Cycle of a Fly

Whether house fly or stable fly, these annoying, filthy creatures make their presence known. Like all insects, the fly has a body divided into three parts - head, thorax, and abdomen - a hardWhether house fly or stable fly, these annoying, filthy creatures make their presence known. Like all insects, the fly has a body divided into three parts - head, thorax, and abdomen - a hard

Story originally posted by Horsecity.com Staff

The House Fly and Stable Fly Go Full Circle Unless the Life Cycle is Broken

Whether house fly or stable fly, these annoying, filthy creatures make their presence known. Like all insects, the fly has a body divided into three parts – head, thorax, and abdomen – a hard exoskeleton, and six jointed legs. Flies also have a pair of transparent wings.

All flies undergo complete metamorphosis with egg, larval, pupal, and adult stages in their development. The female fly deposits her eggs in organic material, such as manure, where the larvae, or "maggots," complete their development, feeding on bacteria associated with their developmental site. When maggots have completed their development they convert their last larval skin into a puparium, a hardened shell within which the pupa develops. While in this hard shell, the pupa transforms into an adult fly, which pops off the end of the puparium and emerges. The rate of development is dependent on species and temperature. The life cycle from egg to adult can be completed in as little as one week during optimal conditions, but typically takes three weeks. Adults mate within one to two days after emerging from their pupal cases.

While humans commonly find adult flies to be the most bothersome, the larval stage should be the prime target for control efforts. Elimination of larval habitat is the preferred method of pest fly suppression; however this is not always the most practical method. SimpliFly™ with LarvaStop™ Fly Growth Regulator breaks the fly’s life cycle by preventing the development of fly larvae. This is accomplished by interfering with the production of chitin, a key component of the insect’s exoskeleton. Chitin is not found in horses.

The common house fly, Musca domestica, is found throughout the world. Adults are about 1/4 inch long with the female usually larger than the male. House flies are dark gray, with four dark stripes down the top of the thorax. They have sponging mouthparts (they cannot bite) and can only eat liquids. When feeding, house flies regurgitate some of their stomach contents on the food, which dissolves it, then they suck it back into their stomach. They leave fecal deposits where they have walked.

While walking and feeding on garbage, fecal material and food, flies may transfer disease organisms (bacteria and viruses) from both inside and outside their bodies. House flies are suspected of transmitting at least 65 human diseases such as typhoid fever, cholera, dysentery, tuberculosis, anthrax, leprosy, food poisoning, pinworms, hookworms, and some tapeworms.

Adult house flies normally live about two and a half weeks during the summer, but can survive up to three months at lower temperatures. During this time they may fly up to 20 miles from their place of birth. Each female lays five to six batches of 75 to 120 oval, white eggs in decaying organic matter such as garbage and human and animal excrement. Horse manure is a perfect breeding medium. It has been observed that as many as 10 to 12 generations may occur in one summer. The house fly overwinters in either the larval or pupal stage under manure piles or in other protected locations.

The stable fly, Stomoxys calcitrans, is 1/4 inch long with a pale spot behind the head, indistinct stripes on the thorax, and seven dark spots on the abdomen. It is a common biting fly pest. Although the stable fly adult is similar to the house fly in size and appearance, it differs in one important area. Stable flies have biting mouthparts that stick out like a bayonet from the front of the head for sucking blood. Unlike many other fly species, both male and female stable flies suck blood. Each fly feeds several times per day, taking only a drop or two of blood at a time. The bite is painful and the fly stays on the animal long enough to obtain a blood meal, then seeks a shaded place to digest it.

The pain caused by the stable fly’s bite as its mouthparts saw into the flesh and draw blood is just one of its hazards. This fly is also an intermediate host of the small-mouthed stomach worm and has been known to transmit such diseases as anthrax, equine infectious anemia, and anaplasmosis. In addition, bite wounds can be sites for secondary infection. It bites mainly on the legs and flanks of horses and is active only during the day. In its normal environment, the stable fly is not considered a pest to man. However, in the absence of an animal host humans are seen as a viable option.

Adult stable flies can fly up to 70 miles from their breeding sites. The average adult stable fly lives 28 days, ranging from 22 – 58 days depending on weather conditions. The female fly deposits eggs in spoiled or fermenting organic matter including manure well-mixed with hay. Each female fly may lay 500 – 600 eggs in 4 separate layings. When temperatures drop, stable flies overwinter as larvae or pupae in piles of larval breeding material.


A pair of flies beginning operation in April, if all were to live to adulthood, would result in 191,010,000,000,000,000,000 (191 quintillion 10 quadrillion) flies by August. Assuming 1/8 cubic inch per fly, this number would cover the earth 47 feet deep.

House flies are hard to swat because they react to movement five times faster than humans do. Sensitive hairs on their bodies send data directly to the wings, so these flies can take off the instant motion is detected. In humans, the sensory data must usually be processed by the brain.

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