Warble fly
| Warble flies | |
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| Ox Warble-fly (Hypoderma bovis) | |
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| Life cycle | |
| Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Arthropoda |
| Class: | Insecta |
| Order: | Diptera |
| Family: | Oestridae |
| Subfamily: | Hypodermatinae |
| Genus: |
Hypoderma Latreille, 1818 |
| Species | |
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Warble fly is a name given to the genus Hypoderma, large flies which are parasitic on cattle and deer. Other names include "heel flies", "bomb flies", and "gad flies", while their larvae are often called "cattle grubs" or "wolves." Common species of warble fly include Hypoderma bovis and Hypoderma lineatum (cattle) and Hypoderma tarandi (reindeer). Larvae of Hypoderma species also have been reported in horses, sheep, goats, and humans. They have also been found on smaller mammals such as cats, squirrels, rabbits, voles, and dogs.
Adult warble flies are large, hairy, and bee-like and brown, orange, or yellow in color. The adults have vestigial mouthparts, so do not feed during their short lifespans, which can be as little as five days.
They are found on all continents of the Northern Hemisphere, principally between 25 and 60° latitude.
The fly lays eggs on the forelegs of large animals. The eggs hatch within a week and penetrate the skin, where they migrate throughout the connective tissues (H. bovis) or to the esophagus (H. lineatum). After a few months, the larvae travel back to the skin surface and cause swellings called "warbles". They remain under the skin, and when destroyed by pressure, the larvae can cause large purulent swellings or anaphylaxis. Upon emergence, the fly leaves holes in the skin. Large numbers of such punctures can render cattle hides valueless.
The migrating larvae can cause damage to meat, as the tunnels they make in the muscle fill with a substance known as "butcher's jelly". Infestations also hinder weight gain and growth in the animals. Milk yields may also decline. Most infections in adult cows are minor due to immunity developed over time.
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Wikipedia