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Previoulsy known as Torymus cingultus, Torymus geranii is a member of the family Torymidae whose females are easy to distinguish from there bright metallic green colourations and very long ovipositors. The ovipositor is used to iject an egg into a gall chamber and the insects that they prey upon include; Helicomyia saliciperda an member of the Cecidomyiidae family in the order of Diptera along with, from the order of Hymenoptera; Andricus curvator sexual, A. kollari agamic, A.lignicola agamic, A. quercuscalicis agamic, Biorhiza pallida sexual, Cynips divisa agamic, Cynips longiventris agamic, Diplolepis nervosa, Dryocosmus kuriphilus, Neuroterus anthracinus (=Neuroterus anthracina) agamic and Trigonaspis synaspis.
As such the wasp tends to be located around Oaks, sweet chestnut and rose. The flight times of T. geranii are from january through to october.
The female measures 2.8-4.6mm averaging 3.4mm excluding the ovipositor.
The head is blue and green metallic in colour with hairy cheeks with red eyes and dark neutral brown ocelli. The short and stout antennae are dark brown with a yellow tinged scape and have one ring and 7 funicular segments.
The thorax is a metallic blue, bronze and green with deep full length notaulices and straw coloured tegulae. The wings are transparent with dark yellow brown veins and pale hairs. The stigmal vein is short but the stigma and uncus are well developed. The legs have metallic green coxae which are reticulated. The rear coxae have a fringe of long white hairs above. The rest of the legs are pale yellow and it has 5 tarsi.
The gaster (abdomen) is metallic green and bronze with more or less testaceous pink at the front and underneath. If no pink is present then it will probably be Torymus auratus. The ovipositor sheaths are dark brown and hairy and measure about 98% of the body length.
The male measures in at an average of 2.5mm with a range of 1.5-4.2mm.
The head is metallic green and lightly sculptured. It has short hairs all over. The eyes are bright red with chestnut to dark coloured ocelli. The antennae are dark grey brown with pale longitudinal sensillae and there is a yellow socket to the scape. The 3rd segment is shorter than the pedicel (see T. auratus).
The thorax is metallic green and covered in short hairs. The notaulices are deep and full length The tegulae are straw coloured leadin to the wings which are slightly yellowish and hairy all over. The veining is strong a stigmal vein is very short with a quite heavy stigma. The legs are variable in the coxae, of which the rear pair have many long white hairs above, which range from reticulate metallic green rear coxae only, the rest being brown, to all metallic coxae, femora and tibia, with pale yellow joints. The remainder of the legs are a variable yellow and there are 5 tarsel segments. The gaster is hairy, lightly whirled and ridged all over with a bronze colouring and a testaceous band near the base.
More detailed descriptions and identification keys are available from Robin Williams at the British Plant Gall Society.
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