Numbers
In North America, 883 species
(1)
About 530 general and 7,000 described species worldwide (
Asilidae Home Page)
Size
5-30 mm (typically 9-15 mm)
Identification
Medium-sized to large predatory flies, often perch in exposed location and make short flies after prey. Typical family characteristics:
top of head hollowed out between eyes, with three
ocelli in this depression (diagnostic character)
body from very hairy to nearly bare
typical body form elongated, with tapered
abdomen, but other forms as well
face usually "bearded", with prominent
mystax
mouthparts modified to inject saliva into prey--saliva contains potent neurotoxic and proteolytic enzymes
mouthparts similar in both sexes, unlike typical blood-sucking flies, such as
Tabanidae
antennae with three segments, third segment elongate and often with terminal
style
Habitat
A variety of habitats, but most diverse in dry, open habitats; larvae usually occur in soil or decaying wood.
Food
Predatory on a variety of other insects.
Life Cycle
Adults lay eggs in the soil or in plants. A few, such as
Mallophora and
Megaphorus form an egg mass on a plant stem (see photo
here). Larvae often predatory, consuming eggs and larvae of other insects in decaying matter. Typically overwinter as pupa, emerge in spring. Life cycle is 1-3 years.
Remarks
CAUTION! Large Robberflies may bite if handled roughly. See Forums discussion
here.
Internet References
Univ. Florida--Featured Creatures, has Key to the Subfamilies of Florida Asilidae
Giff Beaton--southeastern robber flies
Herschel Raney--Arkansas and other robber flies
Strickland's site--excellent scans
