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Thick-headed Fly - Physoconops sp. Our Physoconops photographs were featured in The American Wildlife Federation's Field Guide to Insects 2007 Diptera Family Conopidae Live adult thick-headed flies photographed in the wild at Winfield, Illinois, USA. |
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Conopids are most frequently found at flowers, feeding on nectar with their long proboscis. This wonderful contraption resembles the spout on the old railroad trackside water towers used during the Steam Era, and the boom used in mid-air refueling operations, albeit with a sucking mechanism instead of offloading. Flies of the family Conopidae are distributed in all the zoogeographic regions except for the poles and many of the Pacific islands. About 800 species are described worldwide, approximately 67 of which are found in North America. The majority of conopids are black and yellow, or black and white, and often strikingly resemble wasps, bees, or flies of the family Syrphidae, themselves notable bee mimics. The larvae of all conopids are internal parasites, most of aculeate (stinging) Hymenoptera. Adults are said to alight and deposit eggs on their flying hosts. |

Thick-headed Fly - Physocephala tibialis
15mm
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![]() Compare to : Vespid Wasp |
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This fly was photographed on a hot day in August, amongst a stand of aster and frost aster wildflowers, alive with thousands of bees, wasps, and flies of all sorts, all in competition for valuable nectar. Since these flies are said to lay their eggs, in mid-flight, on the host, the close association with Hymenoptera is beneficial to the fly in more ways than one. Their mimicry of the stinging hymenoptera provides the fly with protection from predators as well. |

If you've ever seen one of these flies, you'll know how the word
ethereal applies to its habit.
Physocephala tibialis
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Robber Flies Family Asilidae |
Syrphid Fly Mallota sp. |