A few weeks ago I wrote about some basswood leaf mining beetles (Baliosus nervosus, Chrysomelidae) that I discovered in some forest leaf litter. They had apparently awoken from overwintering and were just starting to become active.
Yesterday I was out in the same mesic southern forest in southeast Michigan and I came across a young American basswood tree (Tilia americana, Tiliaceae). I got a bit excited, hoping to find some evidence of these leaf mining beetles. I was not disappointed:
In the photo above you can see at least four adult beetles and some skeletonized basswood leaves. In my initial post I pointed out that leaf mining insects have larvae that feed within the leaf tissues, creating “mines” in the leaves (example). The interesting thing here is that this leaf damage doesn’t seem to be caused by larvae, it’s more consistent with chewing damage caused by adults.
I also found adults that appeared to be in the process of eating:
So in addition to the larvae mining the leaves, the adults appear to eat them as well. That wasn’t all they were doing, however:
A lot of them were mating, and I imagine the females will soon lay eggs on the leaves. After hatching, the larvae will inevitably start chewing their way through the foliage. After getting fat and pupating, they’ll overwinter in the leaf litter on the ground and start it all again next year.