Robber Fly – Tolmerus species

Robber Fly – Machimus species
Family Asilidae – Robber Flies

Live adult robber flies photographed in the wild at various North American locations. Size: 15mm
Flies Index | Flies Main | Tachinidae | Syrphidae | Bombyliidae | Asilidae

Robber flies are fun to watch.  I watched the specimen hunt for perhaps 20 minutes – he made numerous attempts to catch various insects in mid-air, including one moth which eluded him three different times. Compared to dragonflies who are fast and agile, robber flies are often slow and clumsy, and miss more often than not. As far as I know, the huge Promachus does not even attempt mid-air captures. I've only ever seen them pounce on their prey who are busy feeding at flowers.

Range: North America east of the Rocky Mountains
Food: Adults suck body juices from small flying insects, larvae prey on insect larvae, especially beetles.
Life Cycle: Female lays eggs in holes in the soil. Larvae tunnel downward in search of prey, pupate in soil close to the surface.
Adults fly July -September.

Robber Fly - Tolmerus species

1.  Fritz Geller-Grimm, "Asilidae"
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. Most flies have compound eyes and mouthparts adapted for piercing, lapping or sucking fluids.
Flies Index | Flies Main | Tachinidae | Syrphidae | Bombyliidae | Asilidae