238 Agricultural Experiment Station, Ithaca, "N. Y. 



The eggs of the summer broods do not differ from those laid by 

 the hibernating adult. The summer eggs, however, hatch in 

 from eight to ten days under the warmer and more even tem- 

 perature conditions. 



Detailed account of a single generation. — A detailed study was 

 made of the second generation of the pest to ascertain any j)ecu- 

 liarities of any of its stages which might be of interest, or of 

 aid in combating the insect. The breeding was done in the 

 Insectarv and field observations were made to verifv the results 

 as far as possible. The cages used consisted simply of a common 

 lamp chimney set on the surface of the soil in a small flower pot; 

 the top of the chimney was covered with Swiss muslin and a vial 

 of water sunlcen into the soil kept the pear branch fresh for 

 several days. These cheap and simple cages have been found 

 very convenient and useful in breeding such small insects, or 

 in getting the number of moults of larvae isolated in them. 



The females of the spring brood began to appear about .lune 

 10, 1892. and many were laying eggs by the twentieth. On the 

 twenty-first, several females were placed in cages on uninfected 

 pear leaves. ^^f^^f'' were laid the following day. An egg is 

 described and figured on page 2.36. When first laid they were 

 tender and easily crushed; but in a few hours the shell became 

 hard and the egg could be dislodged and quite roughly liandlc-d 

 without injuring it. The shell was found to be impervious to 

 several oils and weak alkalies. The acids and strong alkriUcs 

 penetrated the shell and killed the embryo. The eggs hatched 

 in from eight to ten days; a day or two before hatching The 

 crimson eyes of the embryo could be plainly seen through the 

 shell near the larger end of the ef:^g. 



The nvmphs which emerged were oval in form and of a pnle 

 translucent yellow color with the abdomen more opaque and 

 darker. Tlie crimson eyes were large and dislinct. The curious 

 creatures were scarcely visible to the unaided eye, measuring 

 only .013 of an inch in length. A slight constriction of the body 

 marked the beginning of the abdomen which i.^ fringed with eight 

 or nine long and several short hairs. The wing-pads were not 

 yet distinguishable. The antennae had but three points, two 



