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Genus Tetraneura

Elm gall aphids

Species Overview: Genus Tetraneura  Tetraneura ulmi 

Genus Tetraneura [Pemphigini]

These are small aphids. The wingless forms have one-segmented tarsi and the winged forms have a simple, unbranched medial vein in the forewing. The 4th antennal segment is usually much shorter than the 5th. Wax gland plates may be present or absent.

There are about 30 species in this genus. At least seven of them host alternate between leaf galls on elm (Ulmaceae) and roots of grasses (Poaceae). The remainder are only described from either elm or the roots of grasses. They usually have a sexual stage in the life cycle. The fundatrices induce stalked, pouch-like red, yellow or green galls on the upper sides of leaves. They are not attended by ants.

 

Tetraneura ulmi (elm-grass root aphid)

Aphids develop within galls on elm (shown in first picture below). The galls are stalked, approximately bean-shaped, smooth and shiny, and coloured reddish-green and/or yellow. The fundatrices are light green with the head, thorax, antennae and legs dark and no wax glands. The alatiform offspring of the fundatrix have a shiny black head, thorax, antennae and legs, greyish black abdominal segments and wax glands (see second picture below). The body length of alates is 1.8-2.6 mm.

 

The winged forms of the elm-grass root aphid emerge from elm galls (Ulmus spp.) in June-July to colonize roots of grasses (Poaceae). Populations without sexual forms occur commonly on secondary hosts. A return migration to elm takes place in autumn. It is found in Europe, across Asia to eastern Siberia and has been introduced to North America.

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Acknowledgements

We have made provisional identifications from high resolution photos of living specimens, along with host plant identity. In the great majority of cases, identifications have been confirmed by microscopic examination of preserved specimens. We have used the keys and species accounts of Blackman & Eastop (1994)  and Blackman & Eastop (2006)  supplemented with Blackman (1974) , Stroyan (1977) , Stroyan (1984) , Blackman & Eastop (1984) , Heie (1980-1995) , Dixon & Thieme (2007)  and Blackman (2010) . We fully acknowledge these authors as the source for the (summarized) taxonomic information we have presented. Any errors in identification or information are ours alone, and we would be very grateful for any corrections. For assistance on the terms used for aphid morphology we suggest the figure  provided by Blackman & Eastop (2006).

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