Notes on East African Aphids VII-Crass and cereal ctem- and leaf-feeding species

Abstract

There are several very similar species of Macrosiphul1l (Sitobion) in East Africa resembling the European M. (S.) fragarire (Walker), which, since they differ only slightly in such characters as the shape of the rostrum and the length of the body hairs, should be submitted to a specialist for identification. Microscope preparations resemble M. (S.) nigrinectaria, figured in Part III of this series. They may be black, blue, brownish, yellow or green in life. M. (S.) avenre (Fabr.) (granarium Kirby, of some authors), only once recorded from East Africa (perhaps a misidentification), differs from the fragarire group in that the siphunculi are only about one and one-quarter times as long as the cauda. M. (Sitobion) sijui Eastop, known only from Kenya where it feeds on Cenchrus and Setaria, differs from other Macrosiphulum in the much shorter siphunculi (Fig. E), the apices of which bear only a few rows of hexagonal reticulation; and the shorter antennre (Fig. D), the third segment of which does not bear rhinaria.Metopolophiul1l dirhodum (Walker), known in Kenya only from Bromlis catharticus, also occurs on cereals in Europe, but this may be a distinct sub-species. M etopolophilll1l differs from Macrosiphulum in that the siphunculum are not reticulated at the apex. Metopolophilum festucre (Theobald), not known from East Africa but important in Europe on cereals, differs from dirhodlll1l in having evenly pigmented antennre, gradually darker from base to apex, whereas in dirhodlll1l the base of the sixth antennal segment is paler than the apex of the fifth; siphunculum three to four and onehalf times as long as the second segment of the hind tarsi and one and one-half to twice as long as the cauda which bears five to eight hairs. In dirhodllm, the siphunculum are two and one-half to three and one-quarter times as long as the second segment of the hind tarsus and one and one-fifth to one and three-quarter times as long as the cauda which bears seven to twelve hairs. The winged forms differ in that festucre has a dorsel abdominal pattern of transverse black bars, while the dorsum of dirhodlum is uniformly pale.