Tetraneura ulmi

Aphid Tetraneura ulmi

Description

On the top side of the leaf are formed follicle-like galls up to 2 cm in size. Their surface is always smooth, hairless, at first green or yellow-green. They are narrowed at the point of contact with the leaf. Inside the galls, a spacious cavity is formed where the development of fundatrices and the 2nd generation established by them takes place. Several galls are usually found on a single leaf. In the place of gall occurrence, the leaf is deformed and changes colour from pale green to yellow. The galls are hairless and often shiny. It attacks numerous species of elm (it is the most abundant on Ulmus minor and much less on U. glabra and U. laevis) and often heavily infests them. It occurs on many places along with other representatives of this genus. It can be confused very easily with similar T. nigriabdominalis (which is widely distributed from East Asia to Europe on Ulmus spp.) and which has hairy (pubescent) galls. Further research is needed on the area of taxonomy and symptomatology of the genus Tetraneura.

Symptom

On the upper side of the leaf there are pocket galls up to 2 cm in size. They narrow at the point of contact with the leaf. The galls are hair-less and often shiny.

Tree Species: Elm

Part of a plant- attacked: Leaf / Needle

Pest significance: Less harmful

Pest Category: Insects

Invasive Species: No

Present in EU: Yes