Tetraneura ulmi (L.) Elm‑Grass Root Aphid

Galls are stalked, approximately bean-shaped (fig. 134D), smooth and shiny, reddish-green and/or yellow (see influentialpoints.com/Gallery), on leaves of various Ulmus spp. (campestris, glabra, minor). Their histology was investigated by Álvarez et al. (2013). Urban (2003a) made a detailed study of its bionomics on elms. T. ulmi occurs commonly in Europe, across Asia to eastern Siberia (Pashchenko 1988a) and northern Japan, and was introduced to North America. Alatae (BL 1.8-2.6 mm) (fig. 117E) emerge in June-July to colonize roots of Poaceae. Apterae on grass roots (Plate 1d) are pale orange yellow, yellowish white or reddish, with head, prothorax, and appendages brown; the body lightly dusted with wax; BL 1.7-2.8 mm. They are found on numerous species of Poaceae (especially Agropyron, Bromus, Dactylis, Deschampsia, Festuca, Holcus, Hordeum, Lolium, Poa, Zea), are invariably ant‑attended, and often in ants' nests. Overwintering occurs commonly on grass roots or in ants' nests, root‑feeding colonies producing rather few sexuparae in autumn. Ivens et al. (2012a,b) used microsatellite DNA analysis to investigate clonal diversity of root-feeding populations in the Netherlands. Zwölfer (1957) made a detailed study of root-feeding populations, including comparison with the closely related and perhaps synonymous Tetraneura longisetosa (Dahl), collected from roots of Brachypodium, Deschampsia and Festuca in Germany. Tetraneura chui Zhang, described from Sorghum vulgare (= bicolor) in China, may also be a synonym. 2n (T. ulmi) =14 (gall generation); Galli & Manicardi reported 2n =14 to 16.

Colopha ulmisacculi

On leaves of slippery and wych elm, producing cockscomb or pouchlike galls on upper surface.

Tetraneura ulmisacculi Patch

Ulmus

Globose, yellowish-green, pink-tinted leaf gall, diameter 1/4 t o1/2 inch, on Ulmus montana [glabra], aphid, summer

Galls of both [T. ulmi and T. nigriabdominalis] are stalked and located on the upper side of a leaf. Galls of T. (T.) nigriabdominalis are hairy, elongate or pouch shaped, usually with a pointed apex, whereas the galls formed by T. (T.) ulmi are smooth and shiny and bean shaped (Fig.3). When mature, the galls of T. (T.) nigriabdominalis are usually bicoloured green and rose-red, and those formed by T. (T.) ulmi are reddish-green or yellowish. Galls of both species can co-occur on the same leaf blade (Fig. 3).