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Vol. L. LONDON, OCTOBER, 1918 No. 10 



POPULAR AND PRACTICAL ENTOMOLOGY. 

 The Fruit-tree Leaf-roller (Tortrlx argyrospila). 

 by l. caesar, guelph, ont. 



It is only during the last five or six years that the Fruit-tree 

 Leaf-roller has been known as a dangerous pest in apple, pear or 

 plum orchards in Ontario. It has evidently, however, been present 

 in the province for many years, for otherwise the writer would not 

 have been able the second year of the outbreak to find it here and 

 there in small numbers in almost every fruit-growing district of 

 the province. 



Up to the present time only three bad outbreaks have been 

 discovered, and these all occurred almost simultaneously about 

 six years ago. One of these was in a ten-acre orchard in the 

 county of Northumberland, another in a larger orchard in the 

 county of Wentworth, and the other in a still larger orchard in 

 the county of Norfolk. The history of the insect in each of these 

 three orchards may prove of interest and possibly of some value. 



The first two years in all three orchards much damage was 

 done, and the owners estimated that from 20% to 60% of the fruit 

 was ruined. In the third year the insect began to decrease in 

 number in both the Northumberland and Wentworth orchards, 

 and has now almost disappeared from them. In the Norfolk 

 orchard there was also a decrease in the third year and comparative- 

 ly little injury since until this year, when a large portion of the 

 orchard is once more severely attacked. All surrounding orchards 

 in each of these Iccalities have remained practically free from the 

 pest. This shows clearly its remarkable tendency to localize 

 itself and remain almcst exclusively in its chosen abode. 



The owners of the respective orchards endeavored on the 

 writer's suggestion to control the insect by very heavy applica- 

 tions of arsenate of lead just before the blossoms opened and again 

 immediately after they fell. After the second season it was seen 

 that arsenicals would not control it, and following the experience 



