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Vol. XLVIII. LONDON, DECEMBER, 1916 No. 12 



POPULAR AND PRACTICAL ENTOMOLOGY. 



The Plum Curculio in Ontario, Nature and Extent of the 

 Injuries, . Conditions Favoring the Insect, and 

 Means of Control. 



Part I — Nature of the Injuries. 



BY L. CAESAR, GUELPH. 



The Plum Curculio is found practically all over the fruit- 

 growing portions of Ontario, and is one of our most destructive 

 and, under some circumstances, difficult insects to control. The 

 name "Plum Curculio" is misleading because the insect attacks 

 not only plums but apples, pears, cherries, peaches, apricots, 

 quinces and, on rare occasions, gooseberries. In our experience 

 apricots are worst attacked, then plums and sweet cherries; after 

 these sour cherries, apples, pears, peaches and quinces in the order 

 named. We have only in one locality seen gooseberries attacked. 



Kinds of hijuries. — There are several kinds of injuries: First, 

 there is the injury due to egg laying and the accompanying crescent- 

 sh'aped scar made by the female almost immediately after the 

 act. There may be anywhere from one to a dozen or more eggs, 

 each with its crescent, tQ a single fruit. If such fruit does not drop 

 prematurely, it is usually either disfigured by the enlargement 

 of the crescent into a brown scar or calloused area, which by its 

 nearly semi-circular shape still shows its origin, or is deformed by 

 a depression caused by the growth being checked at the point 

 of oviposition but being continued all around it. There may be 

 several of these depressed areas, some of them quite deep, on a 

 single fruit. This type of deformity is very common on apples 

 and pears but much more rare on other fruits. Some of the apples 

 and pears are so much misshapen that they are totally- unfit for 

 market. Such fruit is often spoken of as being "knobby." The 

 pear has the habit of producing stone cells at the injured places. 



