Deer Fly – Chrysops calvus

Deer Fly – Chrysops calvus
Family Tabanidae – Horse and Deer Flies
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Live adult deer flies photographed at Lockport, Illinois. Size: 10mm
Deer Fly Head detail
Here's a good look at that nasty proboscis and those wild eyes

Chrysops calvus is about 8 mm long and has a dark-grey to black abdomen. The wings have smoky-gray markings. These flies are active from spring to fall. (1) Their breeding sites in marshy areas bring them into contact with humans, and their habit of hovering around the head and shoulders and biting people can really piss one off. They are known for following moving animals and repeatedly buzzing the head; I wear a hat when walking in the sunshine when these flies are active. They can really take a swat, too, and get up and fly off – a disconcerting occurrence when you think you've dealt a death-blow to an annoying bloodsucker!

Deer Fly - Chrysops calvus

Adult deer flies (Chrysops spp.) are 6 to 12 mm long, with striped or banded wings and striped or solid-colored body. These deer flies are distinguished from clegs, which have banded eyes and spotted wings. Larvae are usually found in the wet soil along the shores of ponds and marshy areas. They are cylindrical and pale yellow to white; there are longitudinal ridges along the body. There are swellings on segments 4-10, and the posterior spiracles are on an extended spine. North American species include: C. callidus, C. ater, C. flavidus, and C. vittatus. Their abundance depends on weather conditions and the availability of prey.

Deer Fly - Chrysops calvus

1. William H. Robinson: Handbook of Urban Insects and Arachnids
2. The Insects of Cedar Creek reference: Chrysops
Flies of North America – Order Diptera. Flies are prevalent in virtually all habitats, with over 16,000 species in North America. Flies can be distinguished from all other insects in that they only have one pair of normal wings. The other pair has evolved into small ball-like structures called halteres. Most flies have compound eyes and mouthparts adapted for piercing, lapping or sucking fluids.
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