Medium to large flies, females take blood; some are pests. The notched posterior margin of abdomnal tergite 1 is unique. Typical characteristics:
stoutly built flies with large squamae (scales above the halteres, also called calypters);
feet with 3 pads (as opposed to 2);
antennomere 3 elongated, made up of several fused parts, sometimes with a prominent tooth at base
veins R4 and R5 fork to form a large 'Y' across the wing tip.
antenna
wing
tarsus
Range
Worldwide and throughout NA; analysis of distribution in NA in (3)
Habitat
larvae mostly in wet soil in marshes/bogs and at water margins; a few spp. in sand/gravel in fast-flowing streams; others also in drier soils(14)
Season
Year round in FL, summer further north
Food
adult females feed on vertebrate blood, usually of warm-blooded animals; males (also females in a few spp. in all 3 subfamilies) visit flowers
larvae mainly carnivorous, a few eat detritus
Life Cycle
larval stage up to 2 or more years, esp. in the north(14)
Remarks
The bite is effected by stabbing with the mouthparts and slicing the skin with scissor-like movements of the finely serrate, knife-like mandibles and smaller maxillae. After capillaries are ruptured, anti-coagulant saliva is pumped out through the hypopharynx, and the blood is lapped up using the labella –mouthparts images (Thomas 2012).
Eyes may have striking color pattern; Knüttel & Lunau (1995, 1997) suggest these colours filter light to improve contrast detected by the eye pigments themselves, and play a role in sexual signalling
The horse flies and deer flies of Idaho Nowierski, R. M. and A. R. Gittins. 1976. Research Bulletin, Agricultural Experiment Station, University of Idaho College of-Agriculture. 96, 1-48.
