March of the larvae, continued

The masses of beetle larvae were not the first to infest the grey alders (Alnus incana) this year.  Nearly as soon as the leaves had appeared in April, large numbers of bluish black beetles appeared on them.

Alder leaf beetles (Agelastica alni) feeding on grey alder (Alnus incana) leaves in April.

These alder leaf beetles (Agelastica alni) spent their time consuming large portions of the leaves -- and mating.

Alder leaf beetles mating.

By mid May, some of the female beetles had eaten so much that their elytra (wing covers) no longer fit over their abdomens.

A female alder leaf beetle in May.

These greatly enlarged females must have then gone on to lay numerous eggs, producing the legions of larvae that would be responsible for even more damage to the grey alder leaves.