unknown on Bistorta officinalis
Bistorta officinalis, Belgium, Prov. Liège, Butgenbach, RN de la Vallée de la Schwalm © Stéphane Claerebout
same leaf, underside
underside 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 upper side of the leaves; in the corresponding depression at the underside one (rarely two or three) white cecidomyiid larvae.
Polygonaceae, narrowly monophagous
According 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.