Thick-headed Flies
What are they?
This is a group of rather strange wasp-mimic flies that get their name from their typically rather heavy-headed look. They can most often be found feeding at flowers during the summer months and, though widespread they are never common. Larvae are parasitic on adult hymenopterans - most often solitary bees. The adults will often intercept a bee in flight, wrestle it to the ground and implant an egg into the abdomen of the host.
Identification
Thick-headed flies look rather wasp-like due to their thin waists, but can be identified as flies by their typical fly eyes and the forked antennae. Most species are largely blackish r brownish in color, usually with bands or markings of white or yellow. Some species can be difficult to identify, but a number can be done in the field by their general shape and color-pattern.
Physocephala tibialis
One of the more frequently seen thick-headed flies, which may be found in gardens and open meadows on flowers during the summer months.
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