Trioza urticae
Trioza urticae is a sap-sucking hemipteran bug in the family Triozidae which creates galls on the leaves of nettles. It was described by the Swedish biologist and physician, Carl Linnaeus in 1758.
Description of the gall
Galls are most obvious in August and September, when young leaves at the top of a shoot, above the summer growth are hairy, crinkled and have depressions containing a flat psyllid nymph. Heavilly infested leaves are stunted and much darker than the unaffected leaves. There are two or three generations a year and psyllid populations are at their peak in the autumn; hence when the galls are easily seen. The autumn generation overwinters in turf or evergreens.Host plants include common nettle, small nettle and Urtica membranacea.