475 



migrants would have tiown to other food-plants. It is thought that 

 the rate of reproduction is considerably affected by the influence of 

 the cell sap on Aphid metabolism, so that, under the same environ- 

 mental conditions, the chances of infestation are greater with some 

 varieties than others. 



Plant-breeding experiments would show whether susceptibility or 

 resistance is a specific Mendelian character. The variety Vicia 

 narbonensis, which is considered by many to be a prototype of the 

 cultivated Vicia faha and most nearly represents the wild pro- 

 totype of the modern cultivated race, has a very low susceptibihty. 

 It "seems feasible to consider tentatively that the factor or factors 

 making for high resistance may have been present in the original wild 

 bean, and that this character has been lost or modified in the process of 

 selection in the cultivated varieties. The improved conditions 

 associated with good cultivation, manurial treatment, etc., may to 

 some extent influence the degree of susceptibility to Aphid attacks, 

 but the indications from the present tests are that these are not the only 

 factors. 



In an appendix the probable error to be discounted in these estimates 

 of infestation is discussed from a statistical point of view. 



CuNLiFFE (N.). Additional Host Plants of OscincUa frit, Linn., among 

 Grasses. — Ann. App. Biol., Cambridge, ix, no. 2, June 1922, 

 pp. 165-168. 



Observations have been continued [R.A.E., A, ix, 533] relating to 

 the utilisation of certain grasses as food-plants by Oscinella frit. 

 Experiments, which are outlined, were conducted to determine also 

 the relative preference for different plants at different periods of the 

 year. In addition to previously recorded winter food-plants. Holms 

 lanatus, Bronms sterilis, Dactylis glomerata and Arrhenatherum 

 avenaceum var. bulbosum are now added. In each of the experiments 

 the great majority of midges were reared on Arrhenatherum spp. To 

 the previously recorded spring food-plants may be added Agrostis alba, 

 Arrhenatherum avenaceum var. bulbosum, Horde um murinum and Poa 

 trivialis. Similar tests with cereals in the spring gave a small emergence 

 of flies— wheat, rye, barley and maize yielding none ; Lolium italicum 

 gave a total of five flies and oats a total of ten. 



Observations on the prevalence of the fly in the field indicate that 

 for the years 1919 to 1921, during which the meteorological conditions 

 were very varied, the periods of high and low prevalence tended to be 

 constant. If this observation is confirmed for another season it would 

 explain the fact that early sown crops suffer the least damage 



Miles (H. W.). A New Pest of Strawberries.— Garrf^-w, London, 

 Ixxxvi, no. 2641, 1st July 1922, p. 318, 1 fig. 



A description is given of Geotrupes spiniger. Marsh., which was 

 found infesting strawberry plants at Bristol. The presence of the 

 larvae on beds where manure was forked in during the winter is 

 possibly due to the female being attracted thereby for egg-laying. If 

 only a small amount of manure is left they move about and feed on 

 the roots or any available vegetable matter. It is also possible that 

 they feed on other organic material if the food prepared by the adult 

 is insufficient. When the larvae feed on the roots their development 



