Stimulopalpus japonicus (Bark Louse)

This insect was so tiny in person that I was not entirely sure it was an insect. My eyes could only pick up a small, moving white dot. Once “blown up” through the camera lens, I saw…what was that? It looks kind of like a baby grasshopper or cricket, except the legs are wrong for that. It’s not a springtail. You can see tiny proto-wings on its thorax, so it’s a baby something which will molt and become an adult, but what does it turn into?

The fine people on have identified this insect as a bark louse nymph, specifically Stimulopalpus japonicus. Native to Japan and southern Asia, the adult bark lice (which have full wings, and actually look like tiny moths) probably stowed away in some shipment or other to the US in the 1950s or so. They have been reproducing here (parthenogenetically — there are no known males in the US!) — ever since.

As adults, bark lice are very small (~2mm) insects which actually look a little like very tiny flies or moths. They are not the same as the parasitic lice found on animals, and probably only picked up that common name because they are so small! Though they gather in large groups on trees and the protective silk webs some species make can be unsightly, bark lice do not hurt the trees they live on at all. They are actually thought to be helpful, as they clean trees by eating things like fungi, mold, algae, dead organic matter and debris. When they’re finished eating, bark lice eat their own webbing, cleaning up after themselves!

A tiny first for me — a kind person on bugguide not only identified this nymph for me, but also noted that mine is the first Florida record for this species on bugguide! (Hey, take your little triumphs where you can get them!)

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