| dc.description |
1. A new species of aphis, Aphis (Doralis) cognatella, found on Euonymus europaeus is described and compared with Aphis (Doralis) fabae, which it closely resembles. This new aphis is brown in colour and has long hairs.2. Two individuals, intermediate in character between oviparae and sexuparae, are mentioned.3. Transference experiments, carried out under somewhat artificial conditions, show that although the aphis is normally found on Euonymus sp., it can exist for some time on Rumex obtusifolius, R. crispus, Chenopodium album, Capsella bursapastoris, Arctium lappa, and Beta vulgaris (flower stalks), which are also host plants of A. fabae, but it does not colonise Vicia faba.4. The sexuparae are apterous and produce males, oviparae and apterae, thus differing from A.fabae, in which there are two sexuparous forms, one an alate gynopara and the other an apterous form found on the summer hosts.5. Olfactometer experiments give no indication of any olfactory response to the odour of E. europaeus leaves. |
