310 Report op the Department of Entomology op thb 



indication of first molt until October 5; after wliich the insect 

 became dormant. 



Summarizing tlie above: The first molts of 91 larvfB were 

 recorded and the period from birth to molting found to vary 

 from 11 to 35 days, the average number being 20.7. The second 

 molts of 87 larvae were observed and the number of days from 

 birth found to vary from 14 to 45 days or an average of 29^ days, 

 while the period from the first to the second molt in the case of 

 five larviB was four days. In all cases there was no constant 

 relationship between the stage of development of the scale and 

 the molts. 



Rate of growth of the scale. — The table on following page 

 shows the rate of growth of the scales of three larvae during the 

 first half of the period of growth. None of the scales lived to 

 mature. As the growth of the insect and its scale is probably 

 at nearly the same rate the measurements are of interest as indi- 

 cating the rate of growth of the insect as well as its scale. 



EFFECTS OF TEMPERATURE ON DEVELOPMENT. 



The effects of temperature on the development of the scales 

 is well understood in a general way. It is a matter of common 

 observation that the larvae are usually more numerous and active 

 during warm than cool days. Also that the half-grown insects 

 withstand severe cold, otherwise they could not endure our win- 

 ters. But it is yet not fully understood whether young scales 

 attached to fruit or nursery stock kept in cold storage will con- 

 tinue to develop, are merely checked, or cannot survive. Also 

 whether mature scales under the same conditions will survive 

 and produce young when brought into higher temperatures. 

 The following data was obtained from larvae placed on apples 

 and kept in rooms having temperatures as follows: Checks kept 

 in insectary and oflQce temperature 72-75° F. developed normally. 

 Room 1 had an average temperature 35° F., Room 2, average 



