THE PEAR LEAP-WOEM. 



17 



Another lot of 53 cocoons gave almost similar results, the days on 

 which the greatest numbers issued being March 16 and 17. 



In 1913 a number of cocoons were examined March 10, and none of 

 the inmates were pupae. On March 13 one newly molted pupa was 

 observed. It was entirely pale green, with black eyes, and measured 

 5 mm. by 1.7 mm. On March 30 this pupa began to turn dusky, and 

 on April 2 the head and thorax were black and the abdomen dusky. 

 This pupa failed to develop, but would have issued as an adult about 

 April 5. On March 28, 1913, a fully formed adult was found inside a 

 cocoon. The pupal stage is passed in from two to three weeks. 



THE ADULT. 



Table XV indicates the adult emergence in Washington of 200 indi- 

 viduals, and their sex, in the spring of 1915. 



Table XV. — Adult emergence of the pear leaf-worm, Wenatchee, Wash., 1915. 



Date. 



Males. 



Females. 



Total for 

 each date. 



Date. 



Males. 



Females. 



Total for 

 each date. 



Apr. 2 

 Apr. 3 

 Apr. 4 

 Apr. 5 

 Apr. 6 

 Apr. 7 

 Apr. 8 





 



1 

 1 





 

 



4 

 1 



12 

 25 

 53 

 52 

 15 



4 

 1 

 13 

 26 

 53 

 52 

 15 



Apr. 9 

 Apr. 10 

 Apr. 11 

 Apr. 12 

 Apr. 13 



Total. 





 

 

 

 



8 

 17 

 7 

 3 

 1 



8 

 17 

 7 

 3 

 1 



2 



19S 



200 



The average length of life of 7 females confined in jars with pear 

 twigs was bh days. Comparing the adult emergence in California in 

 1914 with that in Washington in 1915, we find that in the former 

 locality the maximum date was March 19, while in the northern local- 

 ity this date was April 6. The activities of the insect certainly com- 

 mence earlier in the year in California, and this is to be expected when 

 we consider the seasonal differences in the two localities, for the activi- 

 ties con-ospond with the period of leafing of the tree. 



Both in Washington and in California the females have been ob- 

 serv<;d to outnumber the males greatly. Out of 200 adults reared at 

 Wenatchoe, Wash., in 1915, only two were males. 



Parthenogenesis occurs in this species, and unfertilized eggs hatch 

 readily, as already has been stated. The larvae live for some time, 

 some of tlutm until the third instar, but it is not definitely known 

 whether any of them over live to maturity. 



NATURAL CONTROL. 



Although the pear leaf-worm is apparently a native species, its natu- 

 ral enemies seem to })c few, and iiuifficiont in controlling it. No para- 

 sites whatev(!r have been retjonlod in California. At Wenatchee, 

 Wash., several old cocoons, each with a small round hole near one end, 



