THE PLUM CURCULIO IN APPLES 



33 



Table 7. — Percentage of Caged Beetles Which Remained Alive in the 

 Insectary at Different Dates in 1927 and 1928. Waltham, Mass. 

 Date 



June 15 

 July 1 

 July 15 

 Aug. 1 

 Aug. 15 

 bept. 1 

 Sept. 15 

 Oct. 1 

 Oct. 15 

 Nov. 1 

 Nov. 15 



Feeding Injury in the Fall 



Fall feeding punctures by the beetles which emerge in the late summer are 

 much fewer than those made by the overwintering beetles in the spring. 

 In 1927 the record of three typical cages of ten beetles each shows that, 

 although their feeding period was only one-third longer, the overwintering 

 beetles made nearly four times as many feeding punctures as the fall- 

 emerging beetles, in addition to having an average of 175 egg punctures per 

 cage. (Table 8.) 



Table 8. — Comparison of the Number of Punctures in Apples Made by 



Overwintering and Fall-emerging Beetles of the Plum 



Curculio in 1927. Waltham, Mass. 



Fall-Emerg-ing Beetles 



Number of Generations 



There is one generation of the plum curculio annually in Massachusetts. 

 Throughout these studies all attempts to rear second generation individuals 

 in the insectary have been unsuccessful. Unfavorable climatic conditions are 

 not altogether the reason for this, since in 1927 the first beetle of the summer 

 brood emerged three days before the last egg was laid by the overwintering 

 beetles, and in 1928 the first beetle appeared eighteen days before the last 

 egg was laid. 



