SAN JOSE SCALE INVESTIGATIONS. I.* 

 THE DEVELOPMENT OF THE FEMALE. 



V. H. LowEi AND P. J. Parrott. 



SUMMARY. 



The females were found to pass through three "well-defined 

 periods during development: The period of activity which fol- 

 lows very soon after birth and during which they move about 

 freely; the period of growth, at the beginning, of which they 

 insert their mouth parts into the tissue and begin to suck the 

 sap and to form the scale; and the period of reproduction, at 

 the close of which they die. 



The young scale insects under observation remained active for 

 an average period of 27.7 hours at temperatures above 70° F. 

 Temperatures below 60° F. caused them to settle very quickly. 



During the period of activity the larvse can cling to insects of 

 various species and may be carried by them to new localities to 

 which these larger insects happen to go from the infested trees. 



The duration of the period of growth was found to average 49.5 

 days. Four distinct stages in scale formation were apparent : the 

 cottony stage, the tufted stage, the black stage and the mature 

 stage. 



The temperature experiments showed the larvae to be unable 

 to develop at an average temperature of 35° F., but able to 

 develop to the black stage at a temperature of 45° F. Adult 

 females were able to survive this temperature three months and 

 to produce young soon after being removed to a temperature of 

 70° F. At 58° F. some of the larvae developed to the adult 

 stage. 



* Reprint of Bulletin No. 193. 



