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.

No abstract

Four experiments in S.E. England (1960–1963) and one in N.E. England (1963) used different methods to expose selectively plants to swede midge infestations in the field. The two methods which were satisfactory in assessing yield losses were 1) marking naturally infested plants and 2) marking artificially infested plants with small temporary cages to confine the ovipositing midges over the plants and comparing the yields with those of nearby clean uninfested plants. The symptoms of attack were recorded and classified as either primary or secondary. The primary symptoms “swollen petiole” and “crumple leaf” were commoner and more reliable indicators of swede midge attack than the secondary symptoms “many neck” and “cabbage top” which could be caused in other ways. Yields of infested and uninfested plants were compared and it was found that the sowing date and tolerance to attack were related. Early sown plants yielded more and were more tolerant to midge attack than late sown plants even when heavily attacked. It seems that only in unfavourable growing seasons this pest would seriously affect yields of swedes. Résumé LES SYMPTÔMES DE L'ATTAQUE PAR LA CECIDOMYIE DU NAVET (CONTARINIA NASTURTII) ET L'EFFET SUR LA RÉCOLTE DES NAVETS Des expérimentations conduites en Angleterre, quatre dans le Sud‐Est (1960–1963) et une dans le Nord‐Est du pays (1963), ont utilisé différentes méthodes en vue d'exposer sélectivement des plantes de plein champ aux attaques de la Cecidomyie du navet. Les deux méthodes qui ont donné satisfaction pour l'évaluation des pertes dues à ces attaques furent: 1° — soit de marquer les plantes naturellement infestées 2° — soit d'utiliser des plantes artificiellement infestées, en les maintenant dans de petites cages temporaires avec des Cecidomyies afin de limiter la ponte à ces plantes, et de comparer ultérieurement les récoltes de ces plantes marquées avec celles de plantes à peu près saines. Les symptômes de l'attaque ont été classés en primaires ou secondaires. Les symptômes primaires «pétiole renflé» et «feuille frippée» étaient plus fréquents et représentent des indicateurs plus valables de l'attaque par la Cecidomyie que les symptômes secondaires: «many neck» et «cabbage top» qui pourraient avoir une autre origine. Les récoltes de plantes infestées et non‐infestées ont été comparées et il a été montré que ces récoltes dépendaient de la date du semis et de la tolérance aux attaques. Les plantes issues de semis précoces produisaient davantage et étaient plus tolérantes à l'égard des attaques de la Cecidomyie, même quand elles étaient fortement attaquées, que celles semées plus tard. Il semble que cet insecte ne puisse affecter de façon sérieuse les récoltes de navet que dans les années défavorables à la croissance de cette culture.

1. The Garden Chafer (Phyllopertha horticola) causes extensive deterioration of the fell grassland in the Lake District.2. The flight period of the adult beetles occurs between the end of May and the latter end of June.3. Eggs are laid in the soil at a depth of about 2½ inches, but the depth varies according to the nature of the soil. The eggs take from 27 to 30 days to hatch in the field.

SUMMARY An attempt was made in 1968 to reduce a wheat bulb fly population in a field in northern England by means of insecticidal seed dressings on early and late‐sown winter wheat. Ethion seed dressing reduced plant and shoot attack and also decreased the number of larvae within the plants on the late‐sown plots but not on the early‐sown. Chlorfenvin‐ phos seed dressing had no significant effect on either sowing. It is concluded that the control of wheat bulb fly populations by the use of these seed dressings on wheat crops in the previous year is not a promising means of control.