TWENTY-SIXTH REPORT OF STATE ENTOMOLOGIST 29 



FRUIT INSECTS 



The Flathead Valley cherry orchards have several insect 

 pest problems. Chief among these is the black cherry aphid 

 (Myzus cerasi Fab.) which sucks sap from the leaves of the suc- 

 culunt terminal growth, causing the terminals to become mis- 

 shapen. On young trees this is particularly undesirable and all 

 of the Flathead cherry orchards consist of young trees. Prac- 

 tically 100 per cent of the Flathead sweet cherry trees were 

 killed in the unseasonal freeze of October, 1935, but the majority 

 of the growers will have their orchards replanted by 1937 or 

 1938. The cherry aphid problem will then become acute unless 

 control measures are carried out. 



Field tests during the 1935 season showed that the cherry 

 aphid could be controlled nearly 100 per cent with a single spray 

 application. The best spray formula proved to be a summer 

 spray oil 2y2 gallons, water to make 100 gallons, and nicotine 

 sulphate (Black Leaf 40) % pint. This was applied after the 

 buds had swollen and showed green on the tips and just as 

 they began to open. (See figure 4) . 



Cherry growers are still somewhat skeptical of controlling 

 the black cherry aphid by spraying. This is occasioned by im- 

 proper spraying in the past. There is little or no chance of con- 

 trolling the aphids after the leaves have curled. The aphids 

 migrate from the cherry trees late in summer after their dam- 

 age is done and this fact often gives the grower the idea that a 

 late season spray killed them, as numerous cast skins are left 

 behind. The spray must be applied early in the spring after 

 the eggs have hatched and before the aphids can seek cover on 

 the trees, for the spray must come in direct contact with their 

 bodies. The entire tree must be drenched with the spray re- 

 gardless of the amount which falls to the ground as waste. High 

 pressure machines are essential to force the spray into crevices 

 of the tree where aphids may be seeking shelter. Probably the 

 only way to convince the cherry grower of the efficiency of this 

 procedure is to conduct spraying demonstrations in representa- 

 tive orchards in each district. 



The cherry fruit fly (Rhagoletis fausta O. S.) is apt to be 

 relegated to minor importance until the cherry orchards come 

 into bearing again. It is much more than a "scare" as indicated 

 in the last State Entomologist Report. Sour cherry orchards 



