172 MAINE AGRICULTURAIv EXPERIMENT STATION. I912. 



length of about 1.75 mm. Ill is 0.4 mm with 17 more or less 

 distinct but not very large sensoria. IV is 0.275 mm with i to 

 3 sensoria. V, 0.25 mm with usually no sensoria except the 

 terminal one. For wing see Fig. 315. 



Fig. 291. 



These Maine collections of this species accord for the most 

 part with Jackson's drawings and account of Aphis aquaticus 

 Jackson except that they run a little larger. 



Fig. 292. R. nymphaeae. Antenna of alate viviparous female. 



Siphocoryne avenae (Fab.) The European Grain I^ouse was 

 abundant in the Station Insectary upon oats and barley the 

 winter of 1909-1910. No. i-io was an Insectary collection, 

 Jan. 5, 1910, comprising apterous and alate viviparous females 

 and pupae. This species also occurs in the apple in Maine. 

 Fig. 310 gives a photograph of the wing. Sanderson (1901b 

 13th Ann. Rept. Delaware Col. Agr. Exp. Sta.) and Pergande 

 (1904a Bui. 44 Div. of Ent., U. S. Dept. of Agr.) give figures, 

 ■descriptions and discussions of this species which characterize 

 it so well that further description is unnecessary here. 



Collection 120-10 from leaf blades of cultivated corn at 

 Orono, Maine, Sept. 14, 1910, comprised apterous and alate 

 viviparous females, nymphs and pupae of this species. Avenae 

 has sometimes considerably affected the wheat crops of Illinois, 

 Minnesota and other wheat growing localities. It has been 

 considered in Canada one of the chief insect enemies of the 

 wheat. Concerning the habits of this species Thomas in his 

 Third Report (1879 P- 53) says "When the winter wheat 

 appears above the ground in the fall, it passes from its hiding 

 place at this time, wherever that may be, probably in the same 

 way that it does from the winter wheat to the spring wheat 

 and oats in the spring, that is by the winged individuals. 



"Here they work upon the leaves and stalks singly, while 

 the weather is not too cold, but when Avinter appears they move 



