none Basing on researches carried out on Stomaphis acquerinoi from a mountain area of northern Tuscany, Acquerino Forest (Pistoia Province), the biology and ecology of that uncommon species are outlined. S. acquerinoi lives on Acer pseudoplatanus L. Colonies of the bark feeding aphid were observed on trunks of young European sycamore trees from May to November. They set in small to large sized colonies on the smooth surface of the bark from the ground level up to four meters in height. Colonies are attended by the ant Lasius fuliginosus (Latr.). No sexuales have been found so far. This Stomaphis species is assumed to overwinter as alate viviparous female. Aphids are strongly parasitized by the Braconid wasp, Protaphidius wissmannii (Ratz.). S. acquerinoi has been recorded also from Mount Amiata, South of Tuscany. Nutrition; Diet; Associations; Parasites diseases and disorders; Parasites; Insect parasites; Hosts; Insect hosts; Ecology; Land zones; Palaearctic region; Eurasia; Europe Protaphidius wissmannii (Aphidiidae); Hemipteran hosts; Stomaphis acquerinoi; Prevalence; Italy; Hemipteran host prevalence Lasius fuliginosus (Formicidae); Mutualism; Stomaphis acquerinoi (Hemiptera); Italy Stomaphis acquerinoi (Aphidoidea); Food plants; Acer pseudoplatanus (sycamore); Colony trunk distribution, hymenopteran mutualism & parasite prevalence; Mutualism; Lasius fuliginosus (Hymenoptera); Hymenopteran parasites; Protaphidius wissmannii; Distribution within habitat; Italy; Tuscany; Pistoia Province; Acquerino Forest; Biology & ecology notes