116 



Heinrich (C). U.S. Bur. Entom. Note on the European Corn Borer 



{Pyrausta nubilalis, HObner) and its nearest American Allies, 



with Description of Larvae, Pupae and one New Species.— JZ. 



Agric. Research, Washington D.C., xviii, no. 3, 1st November 1919, 



pp. 171-178, 5 plates. [Received 7th January 1920.] 



This paper is written with the object of enabling the positive 

 identification and separation of Pyrausta nubilalis, Hb., from its 

 nearest American allies [see also R.A.E., A, vii, 395]. The new species 

 described is Pyrausta ainsliei, the food-plants of which include maize. 

 Polygonum, Ambrosia, Xanthium and Ewpatorium. 



Baker (A. C.) & Turner (W. F.). U.S. Bur. Entom. Apple-Grain 

 Aphis.— JZ. Agric. Research, Washington, D.C., xviii, no. 6, 15th 

 December 1919, pp. 311-324, 1 fig. 



When the studies on the apple-grain aphis recorded in this paper 

 were made in Virginia during 1914-1916, opinions were divided as 

 to whether migration was annual or biennial. At that time also the 

 species was known as Aphis avenae, ¥., but it is now considered that 

 the species concerned is Rhopalosiphum prunifoliae. Fitch. 



A number of species that have very similar summer forms on grain 

 have in the past been confused. These include R. prunifoliae, Fitch, 

 which winters on apple and migrates to grains and grasses, and has 

 been incorrectly recorded as Aphis avenae, F. ; R. padi, L., which is 

 abundant in Europe upon bird-cherry and migrates to grasses in the 

 summer, and of which A. avenae, F., is a synonym and also probably 

 A. pseudoavenae. Patch ; and A. cerasifoliae, Fitch, which is common 

 on choke-cherries and in its summer forms on grass, is almost indis- 

 tinguishable from the two former species. A number of other species 

 with very similar summer forms occur, but these are either undescribed 

 or their life- histories are not fully known. 



R. prunifoliae, with which the present paper deals exclusively, 

 deposits its winter eggs mainly on the small branches of the lower 

 portions of apple trees, generally on the fruit spurs, in scars, or exposed 

 on the twigs and small branches. A few of these eggs hatch during 

 March or earlier, but the young nymphs are usually killed off by cold. 

 The main period of hatching is from 3rd to 10th April. The average 

 duration of the nymphal period is 13 days, the total life of the stem- 

 mothers varying from 23 to 49 days. The average number of young 

 produced by seven stem^mothers examined was 99. By the time the 

 young stem-mothers were feeding the majority of the buds had begun 

 to open and the insects clustered upon the terminal buds, the leaves of 

 which had completely expanded by the time they wer^ adult. Their 

 young migrated, almost immediately after birth, to the under-surface 

 of the leaf. In 1915, four generations after the stem-mother were 

 bred on apple. Each of these was partly apterous and partly alate 

 but under normal conditions it seems as though the 4th generation 

 is invariably winged. The average length of Ufe of the spring apterous 

 form was 31 days ; the average nymphal life of the spring migrant 

 forms varied from 8 to 12 days, the variation being closely connected 

 with variations in the mean temperature. The spring migration 

 lasted from about 1st May to 7th June. No general migration occurred 



