Microdon
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Hover flies (family Syrphidae) of the genus Microdon are unusual among the Diptera. Like other members of the subfamily, they are myrmecophiles, meaning they inhabit the nests of ants. Over 350 species are known worldwide, with the greatest diversity being from the tropics; 30 species are known from North America (Thompson 1981).
[edit] Appearance
Microdon adults look more or less like typical flies. Like some other hover flies, they are generally robust and very hairy, often closely resembling bees. They are between 8 and 15 mm long. The antennae are rather long, with the last (third) segment nearly as long as, or sometimes significantly longer than, the first segment; the antennae are nearly as long as the fly's face. These flies are clothed in black or pale (white or golden) hairs, and are themselves either black or metallic green or blue.
The real oddity of the genus Microdon is in its larvae and pupae. These are dome-shaped and look like stout little slugs. Their appearance originally led scientists to describe them as mollusks and scale insects (Duffield 1981). They are slow moving. Most have the spiracles on a peg-like protuberance extending from the end of the abdomen.
[edit] Behaviour
Adult Microdon flies do not behave like other syrphid flies: they do not hover around flowers but instead remain very near the ant colonies which serve as larval hosts.
Larvae may be found very deep in ant colonies. Some species actively feed on ant larvae in the colony (Duffield 1981), others are speculated to be scavengers. Microdon larvae are more or less restricted in their ant host species. Some Microdon have only ever been found in the colonies of a single ant species, while others are restriced to related ant species or genera. Because these flies have such cryptic life cycles, biological information on most species is limited.
[edit] References
- Duffield, R.M. 1981. Biology of Microdon fuscipennis (Diptera: Syrphidae) with interpretation of reproductive strategies of Microdon species found north of Mexico. Proceedings of the Entomological Society of Washington 83: 716-724.
- Thompson, F.C. 1981. Revisionary notes on Nearctic Microdon flies (Diptera: Syrphidae). Proceedings of the Entomological Society of Washington 83: 725-758.
