Orgy in Nelson

I suspect that Saturday’s orgy in Nelson is an annual event. The participants are almost certainly mayflies.

In the comments to a subsequent posting, Orgy swarm redux, it was finally settled that these insects are caddisflies.

Mayflies live as adults only for a few hours (a few species live for two days) and then they die. That short life is spent in group mating. The males start a mating dance by repeatedly flying upwards and then drifting downwards. Soon females join in and an orgy on the wing begins.

I missed last evening’s grand event. Arlene Anderson watched it and sent me her pictures. Will the mayflies hold another orgy tonight? Probably not; maybe next year.

The males start by flying into the wind. As with other insects that form mating balls, these mayflies have picked a marker, a tree, so as to maintain group cohesion.

Mayflies typically mate near the water where the eggs will be deposited. The Lake, of course, lies between the marker tree and the distant mountainside.

Arlene Anderson’s pictures are used with permission.