Bug FAQSplayed Deer Fly
Chrysops caecutiens · Order: Diptera · Family: Tabanidae
Also called: Splayed Deerfly
Source: Wikipedia
Adults are about 8.5 to 10 mm long and have a glossy black thorax with yellow-brown hairs and a black inverted-V on the abdomen. They live in shaded marshes and damp woodlands across most of Europe, the eastern Palearctic and the Near East, and are active from May through September.
Source: Wikipedia
How to recognize it
The middle part of the body (mesonotum and scutellum) is glossy black with yellow-brown hairs, and the abdomen shows a distinct black inverted-V marking.
Source: Wikipedia
Size
Adults reach a length of about 8.5 to 10 mm (0.33 to 0.39 in).
Source: Wikipedia
Does it bite or sting?
When they bite, they inject saliva containing an anti-coagulant that keeps the blood from clotting.
Source: Wikipedia
Where it lives
They prefer shaded marshlands and damp woodlands.
Source: Wikipedia
What it eats
Larvae feed on algae and organic matter in moist, muddy soils. Adult females bite mammals, including humans and roe deer, to obtain blood for egg development.
Source: Wikipedia
Life cycle
Adults are on the wing from May to September.
Source: Wikipedia
When you see it
They are active during the months of May through September.
Source: Wikipedia
Where it is found in the US
Recorded in 1 of 51 states and DC. Most records: New Jersey.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
More photos
Questions people ask
Do splayed deer flies bite people?
Yes, adult females bite mammals to obtain blood for egg development, and their bite includes an anti-coagulant saliva.
Source: Wikipedia
Where can I find splayed deer flies?
They live in shaded marshlands and damp woodlands across most of Europe, the eastern Palearctic, and the Near East.
Source: Wikipedia
Same family (Tabanidae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Chrysops_caecutiens
Look it up elsewhere: GBIF · iNaturalist · BugGuide · Wikipedia
Text written 2026-10-23 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-22.