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MONTANA EXPERIMENT STATION BULLETIN 366 



concentration again occurred. Here the maximum number of 

 moths collected from one trap at one inspection was 54. 

 Populations indicated by the magnitude of some of the collec- 

 tions of this year are of considerable importance to apple 

 growers. 



By means of the traps it is not only possible to time cover 

 sprays, but comparisons may be made, from year to year, as 

 to the upward or downward trend in codling moth populations. 



POTATO PSYLLID 



(Paratrioza cockerelli Sulc.) 



The Potato psyllid (also called the tomato psyllid) was gen- 

 erally present throughout Montana in 1938. This pest appeared 

 on both tomatoes and potatoes, but on the latter a "purple-top" 

 disease caused by the insects greatly increased the damage. 

 Potatoes, especially early varieties, were seriously affected by 



Figure 11. — Psyllid nymphs on tomato leaf. Notice the eggs on the edge of 

 the leaf. Approximately 6 times natural size. 



