THE PEAR LEAF-WORM. iin 
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 pupe. On March 13 one newly molted pupa was 
observed. It was entirely pale green, with black eyes, and measured 
5mm. by 1.7mm. On March 80 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 
Aptil 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 X V.—Adult emergence of the pear leaf-worm, Wenatchee, Wash., 1915. 
Total for 
each date. 
Total for 
each date.|| Date- Males. | Females. 
Date. Males. | Females. 
Apr. 2 0 4 4 Apr. 9 0 8 8 
Apr. 3 0 1 1 Apr. 10 0 17 17 
Apr. 4 I 12 13 || Apr. 11 0 % 7 
Apr. 5 1 25 26 || Apr. 12 0 3 3 
Apr. 6 0 53 53 Apr. 13 0 1 1 
Apr. 7 0 52 5 
Apr. 8 0 15 15 Total. 2 198 200 
The average length of life of 7 females confined in jars with pear 
twigs was 54 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 correspond with the period of leafing of the tree. 
Both in Washington and in California the females have been ob- 
served to outnumber the males greatly. Out of 200 adults reared at 
Wenatchee, Wash., in 1915, only two were males. 
Parthenogenesis occurs in this species, and unfertilized eggs hatch 
readily, as already has been stated. The larve live for some time, 
some of them until the third instar, but it is not definitely known 
whether any of them ever live to maturity. 
NATURAL CONTROL. 
Although the pear leaf-worm is apparently a native species, its natu- 
ral enemies seem to be few, and inefficient in controlling it. No para- 
sites whatever have been recorded in California. At Wenatchee, 
Wash., several old cocoons, each with a small round hole near one end, 
