Adults are usually about 7–11 mm long.
Fine-art photographic collection
Myopa vicaria
A fly that attacks adult bees in mid-air and turns the living host into food for a single hidden larva.
About this species
Myopa vicariaWalker, 1849
Information reviewed15 July 2026
Myopa vicaria is a North American thick-headed fly. Adults visit flowers, but females are parasitoids that intercept bees and insert an egg into the host’s abdomen.
Taxonomy
Animalia · Arthropoda · Insecta · Diptera · Conopidae · Myopa
Accepted taxon. · checked 2026-07-15
North AmericaBroad range and selected reference localities — not a complete occurrence map.
North America
Flower-rich woodland edges, meadows and sites used by solitary bees.
Adults fly in spring and early summer, often around flowers visited by bees.
Adults take nectar; larvae develop internally in adult bees.
Solitary parasitoid.
What makes this species remarkable?
The female seizes a flying bee, curls her abdomen beneath it and forces an egg between the host’s abdominal plates during a struggle that may last only seconds.
The larva develops inside an adult bee rather than a helpless grub, consuming internal tissues while the host continues moving and foraging for part of the infection.
Myopa vicaria has been reared from the specialist mining bee Andrena regularis, linking the parasitoid’s life cycle to the brief spring flowering of the bee’s own host plant.