Tenthredinidae

on Alchemilla

Tenthredinidae on Alchemilla xanthochlora

Alchemilla xanthochlora, Belgium, prov. Namur, Graide © Jean-Yves Baugnée

Tenthredinidae on Alchemilla xanthochlora

underside

parasiet

Probably this is an oviposition scar caused by a sawfly, fam. Tenthredinidae. That would explain the slight swelling and the tiny would at the upperside. It is known of several sawflies that the freshly emerged larvae live endophytically for a short time, before starting to live freely. There are sawfly species known displaying this behaviour (like Empria testaceipes), but without knowledge of the larva an identification is not possible. (Thanks to Andrew Liston and Marko Prous for comments.)

mod 29.ix.2017