Desmometopa

Loew, 1866

freeloader flies

Species Guides

Desmometopa varipalpis(freeloader fly)

Desmometopa is a of freeloader flies in the Milichiidae containing more than 50 described . These tiny flies are notable kleptoparasites, frequently observed feeding on prey captured by spiders, praying mantises, and assassin bugs. They appear within seconds of a securing prey, taking advantage of the kill without contributing to its capture. Predators generally ignore them due to their minute size.

Desmometopa by (c) Nikita Gerasin, some rights reserved (CC BY), uploaded by Nikita Gerasin. Used under a CC-BY license.

Pronunciation

How to pronounce Desmometopa: //ˌdɛz.moʊ.məˈtoʊ.pə//

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Identification

Extremely small body size distinguishes Desmometopa from most other flies. Identification to level requires examination of wing venation, antennal structure, and other microscopic features typical of Milichiidae. Field identification is tentative; definitive determination requires specimen examination by a dipteran .

Images

Distribution

Records exist from Denmark, Norway, and Sweden; actual distribution likely broader given the 's documented presence in North America through observational reports.

Diet

Feeds on bodily fluids of prey captured by other . Has been observed feeding on wrapped honey bees and other prey secured by spiders, praying mantises, and assassin bugs.

Behavior

Engages in kleptoparasitism, arriving within seconds of a capturing prey. Multiple individuals may aggregate on a single food source. Predators do not chase them away or attempt to consume them, apparently because their small size makes them unprofitable prey.

Ecological Role

Acts as a kleptoparasite in -prey interactions, extracting nutrients from kills made by larger predatory arthropods. This represents a commensal or parasitic relationship that reduces the net energy gain for the primary predator.

Similar Taxa

Other Milichiidae generaSimilar minute size and kleptoparasitic ; distinguished by subtle morphological features requiring examination

More Details

Taxonomic uncertainty

Field reports consistently identify freeloader flies as 'probably Desmometopa' or 'likely Desmometopa' based on behavioral observations. Martin Hauser, Senior Insect Biosystematist at CDFA, has cautiously assigned this identification to observed specimens while noting that definitive identification requires detailed examination.