Monthly Mystery #4: Little Nothings Stuck to Trees

That title could describe many of the things with which I concern myself, but what I have in mind here are some very specific little nothings.  In March 2011, Tom Murray posted this photo to BugGuide, wondering what was this ~3-mm perforated object he had found on a beech tree.  If I see an isolated little mystery thing like that, and especially if I don’t see it in person, I can just shrug it off without worrying too much about it, as I did in this case.  But then one day in October, I started seeing these things everywhere I looked.

That day, they were all on young black birches, but I’ve since seen them on red maple and witch hazel saplings; I’m sure they’re placed indiscriminately, and just show up better on relatively smooth surfaces.  They are always oriented vertically, as in the photo above, but I’ll show some examples sideways since that works better with the WordPress format.

That first one is about 2 mm long and is fairly typical; there is always a row of holes on either side, and sometimes a central one at the bottom.  I’m not sure if the material is mud or excrement.  Here’s a side view of a particularly long one:

The same one, viewed head-on:

In this one, the holes apparently haven’t opened up yet:

A few times, I’ve found one that instead of having empty holes, had these things where the holes would be:

I can’t tell if they’re the remains of eggs or larval exuviae, but either way, I think it’s clear that these objects are egg cases.  I can’t think of anything other than a beetle that would cover its eggs with mud or excrement stuck to the side of a tree.  I have yet to find fresh examples, but I would bet they’re made in the spring.  A close-up of the last one:

And one last variation:

If I ever find fresh ones, of course, I’ll collect them to see what hatches out.

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