Dance flies are known for their mating swarms, in which large numbers flies, sometimes all of one gender, fly up and down in a defined area. These swarms sometimes occur during daylight, but most often at dusk when they are very difficult to see. Male dance flies of some species are known to capture smaller insects and wrap them in silk, then fly about offering the prey to receptive females in the swarm. They have even been known to offer empty balls of silk in an effort to deceive females into mating with them. It is not known how often this practice is successful, however, one would think evolutionary pressures would have eliminated the deceptive strains were it not a viable reproduction tactic. |
