Andricus infectorius
Scientific classification
Domain:	Eukaryota
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Insecta
Order:	Hymenoptera
Family:	Cynipidae
Genus:	Andricus
Species:	A. infectorius
Binomial name
Andricus infectorius ( Hartig, 1843)

Andricus infectorius is a species of gall-forming wasp. The species was named by the German biologist Theodor Hartig, in 1843 and is found in Europe.

The asexual generation is a 10–20 mm spherical gall, found from late-May through to October when it matures. Found on the terminal bud of a branch, it is initially green and as it matures darkens to dark brown; falling to the ground in the winter. ^{[1] [2]} The gall is found on Hungarian oak ( Quercus frainetto), sessile oak ( Quercus petraea), downy oak ( Quercus pubescens) and pedunculate oak ( Quercus robur). ^[2]

Oak gall wasps often have two generations per cycle, with one sexual and one asexual; each creating different galls. According to Milan Zúbrik et al. (2013), the sexual generation of the gall is unknown, but likely to be on Turkey oak ( Quercus cerris). ^[1] A very small, ovoid gall on the catkins of Turkey oak may be the sexual generation. ^[2]

This species has been found in some western and central European countries but is absent from Belgium, Germany, Spain and Switzerland. ^[3] It has recently been found in Great Britain. A 2013 gall found on Trengwainton Carn, near Penzance, Cornwall was initially identified as Andricus inflator. According to Dr C Leach of the British Plant Gall Society, it is more likely to be A. infectorius. ^[4]