Proceedings, 1920. 107 



The European Grain-aphis (A. avenae) has a similar life-history to the 

 rosy aphis, but it uses the grain and grasses as alternate hosts instead of 

 plantains. The only important point — this aphis hatches ten days earlier. 



Aphis-control. — Buds too far expanded makes spraying difficult. In 

 all recommendations for spraying it is stated that the best results attend a 

 dormant spray as the buds are nicely broken. It costs money to spray; 

 often not desirable ; depends on degree of infestation and on early spring 

 temperatures, etc. There is a certain stage in the embryo which is suscep- 

 tible to outside agencies. A high temperature of 65^ Fahr. in February 

 often kills most aphides. The study is a very complicated matter; the 

 critical temperatures are not yet determined. In dry air 4 per cent, eggs 

 hatch; in 22 per cent, moisture, 12 per cent.; in 63 per cent, moisture, 20 

 per cent. ; in 100 per cent, moisture, 36-46 per cent, hatch. Lime-sulphur 

 tends to harden shell and nicotine tends to penetrate. Spray i-y lime- 

 sulphur and nicotine 1-500. 



VICTORIA, B.C. : 



N, Printer to the Kiiif's Must Excellent Stujesly. 

 1920. 



