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Vesicular sedge aphidOn this page: Identification & Distribution Other aphids on the same host
Identification & Distribution
Adult apterae of Vesiculaphis theobaldi are elongate oval in body shape. They are variable in colour, yellowish green, pale to mid-green or brownish-orange green to almost black. The head is broad, with the width between (but not including) the eyes wider than its maximum length. The front of the head is produced into three large separate processes between the antennal bases, each bearing spine-like hairs (cf. Vesiculaphis caricis in the Far East, which has the front of the head produced as a ledge). The ventral side of the head has rows of spinules. Antennae are much shorter than the body, and the antennal terminal process is 1.37-1.8 times as long as the base of segment VI. The apical rostral segment (RIV+V) is 1.09-1.21 times the length of the second hind tarsal segment (HTII). Abdominal segments are clearly demarcated. The siphunculi are very scabrous ventrally, and are swollen over most of their length, narrowing sharply just before flange; they curve inwards at the base and outwards at the apex forming a shallow S-shaped curve, and are about 3 times the length of the cauda. The body length of adult Vesiculaphis theobaldi apterae is 1.7-2.1 mm.
Image above copyright Ed Baker, all rights reserved.
Alatae have only one very low median process on the head. The antennae are about 0.7 times the body length, and have 20-35 secondary rhinaria on antennal segment III, 8-17 on segment IV, and 4-11 on segment V. There are dark marginal sclerites on the abdomen, and incomplete sclerotic bands on segment VII and VIII.
The clarified slide mounts below are of adult viviparous female Vesiculaphis theobaldi : wingless, and winged.
Vesiculaphis theobaldi feeds on the undersides of leaves of many species of sedge (Carex), and has also been recorded from hare's-tail cottongrass Eriophorum vaginatum and sea clubrush (Scirpus maritimus). It is mainly found in shady and humid situations, and is attended by ants. It remains all year on Carex. It produces oviparae and alate males in autumn, but viviparous females may be found through the winter months in England. Vesiculaphis theobaldi is widely distributed in Europe, and eastward to west Siberia.
Other aphids on the same host
Vesiculaphis theobaldi has been recorded on 18 species of Carex (Carex acuta, Carex brizoides, Carex crawfordii, Carex cuprina, Carex diandra, Carex divulsa, Carex echinata, Carex elongata, Carex filiformis, Carex muricata, Carex ovalis, Carex panicea, Carex paniculata, Carex pilosa, Carex pilulifera, Carex remota, Carex sylvatica, Carex vulpina).