Cecidostiba semifascia (Walker 1835)

Cecidostiba semifascia is a parasitoid of the family Pteromalidae. As such it parasitises many members of the gall forming family of Cynapidae such as; A. kollari agamic, A. quercuscalicis agamic, Aphelonyx cerricola agamic, Biorhiza pallida sexual and Neuroterus saliens sexual galls. The flight times of this wasp are from march to april then from january through to september and then again in november.

The female measures from 1.7-3.3mm with an average of 2.6mm head and body.
The head is metallic bright green with gold tints, a reticulated sculpture in the clypeus among the striae and no notch. The eyes are large and yellow brown in colour and the ocelli are red brown. The antennae are brassy with 2 rings and 6 funicular segments which darken at the joints. The scape is long and translucent gold and pedicel is darker and flask shaped. The flagellum are not tapered but have conspicuous sensillae and decumbant hairs, and the club is not enlarged.
The thorax is bright metallic green with gold tints, a reticulated mesoscutum with black hairs. There are no notaulices and the reticulated scutellum has 2 longitudinal rows of black inward facing spines. The tegulae are dark brown and glossy, leading to the wings which are clear with a pale brown cloud behind the stigma, more or less depending on the individual and quite often not visible. The veins and hairs are dark. The stigmal vein is long as is the post marginal vein. The stigma is longer than it is wide, with a small uncus. The legs have reticulated metallic green coxae with contrasting yellow trochanter and trochantellus, a dark brown femora and the tibia being pale yellow with a darkened top (C. fungosa being all yellow). The 5 tarsel segments are yellow.
The gaster (abdomen) is segmented, the first segments is glossy dark metallic green, whereas the rest is dark bronze/purple. The gaster is sessile and its shape is triangular from the side. The ovipositor sheaths are not visable.

The male measures 1.2-2.5mm averaging out at 1.7mm
The head is metallic bright green with gold tints, a reticulated sculpture in the clypeus among the striae and no notch. The eyes are large and very dark neutral brown in colour with a paler ring around the circumference and the ocelli are large and red brown. The antennae are brassy with 2 rings and 6 funicular segments which darken at the joints. The scape is long and translucent gold and pedicel is darker and flask shaped. The flagellum are not tapered but have conspicuous sensillae and pale and decumbant hairs, and the club is not enlarged.
The thorax is dark metallic green with a reticulated mesothorax with black hairs. There are no notaulices and the reticulated scutellum has 2 longitudinal rows of black hairs. The tegulae are dark brown and glossy, leading to the wings which are clear with a pale brown cloud behind the stigma, more or less depending on the individual and quite often not visible. The veins are dark and the hairs are brown. The stigmal vein is long as is the post marginal vein. The stigma is longer than it is wide, with a small uncus. The legs have reticulated metallic green coxae with contrasting yellow trochanter and trochantellus, a dark brown femora and the tibia being pale yellow with a darkened top (C. fungosa being all yellow). The 5 tarsel segments are yellow.
The gaster (abdomen) is segmented, the first segments is glossy dark bronze brown without sculpture, whereas the rest has fine transverse sculpting. The gaster is sessile and its shape is long and thin from the side.

More detailed descriptions and identification keys are available from Robin Williams at the British Plant Gall Society.

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