My neighbour recently emailed asking if I could help identify a beetle infestation on a tree in his back garden. When I popped over to take a look, I recognised them as leaf beetles, though I was unsure of the species. I couldn’t find them in my field guides, but if my tree-identification skills were a bit sharper, I might have guessed, as a quick Google revealed that they were alder leaf beetles (Agelastica alni).
They had colonised the lower third of the alder, devouring the foliage from the ground up. The leaves were riddled with perforations, many munched down to the midrib, leaving just enough structure for the beetles to get back to the main stem. Though winged and capable of flight, they seemed to prefer grazing on foot.
