? on Persicaria bistorta
? on Persicaria
Persicaria bistorta, Belgium, Prov. Liège, Butgenbach, RN de la Vallée de la Schwalm © Stéphane Claerebout
same leaf, underside
underide of a leaf, with three occupied galls close together
a singe larva, in drop of digestive liquid
sometimes two larvae share a gall
one or more inconspicuous bumps on the upperside of the leaves; in the corresponding depression at the underside one (rarely two or three) white cecidomyiid larvae.
Polygonaceae, narrowly monophagous
Accordig to Buhr rarely also on Persicaria amphibia.
It is not known which species is involved, despite the fact that Buhr, under # 4980, cites several papers referring to this gall.