The Oat Bird-Cherry Aphis, Rhopalosiphum padi, L., and Comparison with R. crataegellum, Theo. (Hemiptera, Aphididae)

Abstract

1. An attempt has been made to elucidate the confusion existing about the biology, morphology and nomenclature of the Oat-Apple Aphis, Rhopalosiphum prunifoliae, Fitch. A close study of the problem confirms the observations made by Börner that at least two distinct species have in the past been included under the name of R. prunifoliae. The names Rhopalosiphum padi, L., and Rhopalosiphum crataegllum, Theo., are adopted for these species.2. Detailed descriptions and figures of the different generations are given and a comparison shows that the two species can readily be distinguished from one another.3. R. padi appears to be of greater importance as a cereal pest than R. crataegllum. The latter species is a widespread pest of pip-fruit.4. An account is given of the overwintering of R. padi on Prunus padus, and the results of experiments on estimating the size of the ova-populations is shown.The author is indebted to Mr. R. A. Harper Gray for allowing him facilities to carry out the investigation; also to Mr. J. A. Dunn for assistance in collecting some of the material and much general help.