Legless larvae with distinct heads Most of these larvae are beetles or flies Diptera. Each of the pictures represents a larval type. The underside usually is flat while the upper side is rounded, giving them a humpbacked appearance. There is a single fleshy leg at the front and back of the body. They are the immature stages of varies species of gnats.
The thorax is wider than the abdomen and many species have a distinct air tube at the end of the abdomen. These larvae live in still water. They live in standing, stagnant water, and especially seldom used drains.
They live in moist, decaying organic matter, especially accumulations of fallen leaves or dead grass. They are common in compost piles and decaying organic matter. Head mostly hidden or no distinct head These larvae either do not have distinct visible heads or the head is withdrawn almost completely into the thorax.
They are fly larvae that with one exception live in wet or moist areas. The distinct head is completely hidden within the thorax. These dingy gray larvae live in decaying organic matter. The dark head is withdrawn into the thorax but part of it usually is visible.
These borers live in tree limbs, branches, and stems. Many flies have this larval type including blow flies, house flies, and fruit flies.
They are good crawlers and resemble small caterpillars but lack a distinct head and legs of any sort. There are thousands of variations of these basic forms but it is usually possible recognize its basic features and to place the specimen in one of the main groups.
Help with larval identification is available thru your local Cooperative Extension office. The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication. Recognizing Insect Larval Types. Insect Metamorphosis: Gradual left and Complete right.
The presence of insects in a corpse is a critical clue towards estimating the time of death for bodies dead for longer periods of time. Because flies rapidly discover a body and their development times are predictable under particular environmental conditions, the time of death can be calculated by counting back the days from the state of development of flies living on the corpse. The larva, or maggot, is the main feeding stage of the fly.
On hatching, first-instar larvae are roughly 2 mm long, growing to about 5 mm before shedding their skin. The second instar larvae grow to around 10 mm before they shed their skins to become third-instar larvae. Third-instar larvae grow to between 15 mm and 20 mm before wandering off as pre-pupae.
Apart from the change in size, the overall form of fly larvae varies little between instars. The most distinctive feature for separating larvae of different instars is the structure of the posterior spiracles, though which the larvae respire.
Some flies produce predatory maggots that feed on other maggots. The predatory maggots of Chrysomya rufifacies are covered with spiny protrusions which deter other predators. Maggots fly larvae are remarkable eating machines. Their front ends are armed with mouth hooks with which they rake in decaying flesh, shredded from the corpse. Their rear ends consist of a chamber, in which their anus and posterior spiracles are located.
They also have anterior spiracles. Spiracles are used for breathing, and the possession of spiracles in a posterior location means that maggots can breath feeding 24 hours a day. House flies contaminate food surfaces by spreading disease organisms picked up on their legs and mouths when feeding on trash, feces and other decaying substances. Plus, they defecate constantly. Like many other pests, the house fly experiences a four-phase life cycle.
Depending on conditions, the developmental time of a house fly from egg to adult may require as little as six days. The life cycle begins when a fertilized female house fly finds a suitable location to lay her eggs, oftentimes on feces, carrion or garbage.
She will reproduce about times, laying batches of about eggs during each round. Female house flies usually only mate once, but are capable of producing between eggs in their lifetime. The eggs, which are white and about 1. Pale-whitish larvae often referred to as maggots emerge from the eggs.
About mm long, these legless larvae feed at the egg-laying site for three to five days. At the conclusion of this period, larvae seek out a dark, dry and cool environment to pupate. Over the course of three to six days, the pupae develop legs and wings, and grow into fully-grown adult house flies.
After two to three days, the adult female house flies are fully ready and able to reproduce, restarting the life cycle. Adult house flies typically live days. House flies are usually only active during the daytime when they will congregate indoors on floors, walls and ceilings. Outside, house flies opt for hanging around plants, fence wires, garbage cans and the ground. At night, house flies can usually be found resting 5 to 15 feet off the ground and close to sources of food.
Positioning themselves in indoor corners and edges, they can survive cold winters by hibernating. House flies tend to stay within miles of where they were born, but they have been documented for migrating up to 20 miles in order to find food.
However, they use their sponging mouthparts to liquefy many solid foods through spitting or regurgitation. Their tongues are shaped like straws to suck up the food. House flies feed on a wide variety of substances such as human food, animal carcasses and garbage. They are particularly attracted to pet waste because of its potent odor.
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