March of the larvae

Although I encountered one moth larva crossing the sidewalk, the hundreds of other insect larvae that I have seen recently have been (not very surprisingly) on leaves.  What is surprising is that nearly all those larvae have been on the same few leaves. 

A group of alder leaf beetle (Agelastica alni) larvae eating a grey alder (Alnus incana) leaf.

These unfortunate leaves belonged to grey alders (Alnus incana) and hosted groups of 20+ beetle larvae.  The larvae not only shared the leaves, but also kept in tight formations as they ate their way across the leaves...

The beetle larvae on another leaf leaving a sinuous trail.

...leaving behind them trails of small holes.  However, some of the grey alder leaves were riddled with considerably larger holes.  To be continued...