103 AFRICAN APHIDIDAE.— Part IL* By Fred. V. Theobald, M.A. The following notes and descriptions of African plant-lice are based mainly on part of the large collection I have received from Mr. F. C. Willcocks, made in Egypt since 1907 ; specimens from Mr. Gerald Bedford, collected in the Transvaal and the Cape ; and a small collection of spirit specimens without any colour notes sent to the Imperial Bureau of Entomology by Mr. T. J. Anderson from Nairobi, British East Africa. The collection made by Mr. Willcocks in recent years contains some hundreds of specimens, many in alcohol and many beautifully mounted, with field notes giving the living colours of most of the species. This very valuable collection seems to be almost complete for Egypt, for in a recent letter Mr. Willcocks tells me he is unable to find any new species. It contains a number of new insects and some well-known European and American species, including the com pest. Aphis maidis, Fitch ; the green pea louse, Macrosiphum pisi, Kalt. ; Macrosiphiim sonchi, L. ; the so-called yellow clover aphis of America, Callipterus trifolii, Monell, which is here shown to be the Aphis {Callipterus) ononidis of Kaltenbach ; the water-plant aphid of Europe and America, Siphocoryne {Aphis) nymphaeae, L.; and the European willow aphid, Lachnus viminalis, Boyer. The bean-root aphid, Tychea phaseoli, Pass., was also sent and the alate female is now described, as well as the first alate female of Rhizobius, apparently referable to Buckton's Rhizobius graminis. A large number of specimens in Mr. Willcocks' collection yet remain to be examined, including species from Zizyphiis, Duranta, artichokes and sycamore figs ; also others from Nairobi and some tubes of specimens sent by Dr. Aders from Zanzibar to the Imperial Bureau. It may be once more pointed out that many specimens sent in spirit with no colour notes are almost impossible to identify with any degree of certainty. Colour is one of the main things in identifying these insects from old descriptions. Until definite structural characters are given we may have to rely on these. At present comparatively httle is known of plant-lice in Europe and America, the only parts of the world in which they have been at all studied or even collected. With increasing information it appears that many species have a world-wide distribution, as for instance Callipterus ononidis, Kalt., which seems to be common to America, India, Europe and Egypt. Owing to the somewhat crude descriptions of many of the older species and the lack of any real structural characters, it is extremely difficult to say if any particular aphid coming from any part of the world is the same or distinct from one coming from elsewhere. Colour alone is of no value, it may cause considerable confusion in identifying these insects, so far as the original descriptions go. One instance ^vill explain this. A wheat aphid sent by Mr. Willcocks from Eg}^pt is undoubtedly Toxoptera graminum, but the colour notes he sends of this insect do not agree with those of this corn pest of Europe and America. On the other hand the aphid described * For Part I. see Bull. Ent. Res., iv., p. 313. (C177) ^2
BioStor
