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A member of the family Eurytomidae, this wasp is parasitoid of cynipid wasps. Synonyms; Eudecatoma biguttata.
The common gall hosts of this species are; A. aries agamic, A. curruptrix agamic, A. grossulariae agamic, A. kollari agamic, A. lignicola agamic, A. lucidus agamic, A. quercuscalicus agamic, Aphelonyx cerricola agamic, Biorhiza pallida sexual, Cynips divisa agamic, C. longiventris agamic, C. quercusfolii agamic. The flight times for this wasp are from february through to october.
The female wasp measures in at 1.9-4.3mm with an average of 3.4mm.
The head is black, sometimes there is a paler area around the eyes and towards the mouth parts. It has a deep glossy, indented vertex, with the rest of the head being reticulate. The eyes are smallish in size, red with dark brown internal net marks. The ocelli are black. The antennae are mid brown with a long, swollen dark pedicle and very long scape. sensillae are present londitudinally and there is one ring and 5 funicular segments, with a slight taper to an inconspicuous club.
The black thorax has sometimes some inconspicuous paler areas. The mesocutem is punctate-reticulate with faint but full length notaulices. The tegulae are dark leading to the wings which are cloudy/transparent and have a dark rectangular fascia, which is bent in the middle and runs over the stigmal vien. The legs have black coxae, femora and the tibia with more or less dark colouration. The joints are pale and the tarsel segments, of which there are 5, are pale chestnut.
The gaster (abdomen) is petoilate and very dark brown and glossy, without sculpturing. The ovipositor sheaths hardly protrude from beneath.
The male is 2.1-2.2mm averaging at 2.1mm in length.
The head is black with paler areas around the eyes and towards the mouthparts, it is glossy with few hairs and sculptured. The smallish eyes are red/brown in colour with black ocelli. The antennae have one ring and 4 funicular segments and are mid brown and hairy with a heavy club, as well as a long dark scape and a longish pedicel.
The thorax is again largely black with some inconspicuous paler areas and hairy. The notaulices are deep and complete, and the mesescutum is heavily punctate-reticulate. The tegulae are mid brown and the wings are cloudy/transparent and have a dark rectangular fascia, which is bent in the middle and runs over the stigmal vien, which is very short. The legs are black and glossy with dirty yellow, contrasting joints and tarsi, of which there are 5 segments.
The petiolate, glossy black gaster is without sculpturing and small, short and blocky in shape.
More detailed descriptions and identification keys are available from Robin Williams at the British Plant Gall Society.
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