Explanation of Names
Greek rampho 'beak' + plus myia 'fly'
~150 described spp. in our area(1)
+ at least 400 undescribed; 450 described spp. worldwide[cite:745518]
Similar to Empis, but wing venation different
n. hemisphere [cite:745518], incl. much of North America
Moist areas, along edges of fresh (and salt?) water.
Noted, as are other genera of this family, for forming mating swarms. Males capture a small insect and offer it as a nuptial gift to a female.
Comments on swarming (paraphrased) from Paul Beuk
Swarms can be all male, all female, or mixed. In single sex swarms, it may be that individuals of the opposite sex do not form swarms but just temporarily join the swarm for mate selection; or each sex may form their own separate nearby swarms, with individuals leaving theirs and entering the others to select a mate.
Different species swarm at different times of day. Some may swarm during the whole day, others maybe only for an hour at dusk, etc.
The location of the swarm is determined by markers. These may be very specific (under a overhanging branch in the sun, so the swarms may move with the sun) or rather 'generally defined' (along a slope, creating a very 'long' swarm, or over the water surface of a brook).
Nuptial gifts are not known for all mating dance flies. They are mostly found in the subfamily Empidinae (in genera like Empis, Rhamphomyia and Hilara...the latter including the balloon flies).