Most species overwinter as larvae. The mouthparts are for tearing and lapping, not piercing. Both sexes feed on nectar, but females require a blood meal for egg laying. Moving and dark objects are most often attacked. A slight drop in temperature or increase in wind will greatly reduce the numbers flying, unless crews can be spotted on the bay.
Rowers are particularly good targets.
Singles and doubles will usually catch the interest of the smaller observational sorties. The younger, less experienced flies attack body parts that the sculler can swat while losing only a single stroke. The wiser flies will dive for the softer, fleshier parts of the sculler's posterior. This tactic inflicts maximum pain, and blood loss, causing screams that will alert the main squadron. Octuples, Eights and Quads are the primary targets of the main squadron.