Frass

Working in the backyard Saturday (the first nice day in over a week) I kept hearing a strange sound.  It sounded kind of like it was starting to rain.  But it was warm and sunny.  What was that noise?

Here's a clue.  Look at those maple leaves.

Here's another clue.  This is a Viburnum that is under the maple trees.

Got an idea yet?


Here is the culprit.  The caterpillar of the Winter Moth (Operophtera brumata).

This is an introduced species that has become a major pest here in Eastern Massachusetts.  They can completely defoliate trees of preferred species (a neighbor has a weeping cherry that is in decline from years of winter moth damage.  She has to resort to spraying to keep this full sized specimen alive).  While a healthy tree can survive defoliation once several years of defoliating can cause the death of the tree.

Oh, that sound?  That's the sound of millions of caterpillars chewing on leaves.  And the dark spots on the Viburnum leaves are the Frass (feces) of all of those caterpillars

No, I'm not kidding, you really can hear them.