April, '14] HODGKISS AND PARROTT: PARASITES OF SAN JOSE SCALE 227 



eggs destroyed. The period of oviposition of the chmch bug covers 

 about two months, while the hfe cycle of the parasite covers a period 

 of only two or three weeks. Thus the eggs of a single female chinch 

 bug are exposed to about three broods of parasites, while the eggs of 

 one brood of chinch bugs are exposed to four or five broods of parasites. 

 Therefore, the percentage of parasitism for a brood of chinch bugs is 

 at least 50 per cent. Experiments conducted in the field and in the 

 laboratory show this to be true. 



President P. J. Parrott: The next paper on the program is 

 entitled "Parasites of the San Jose Scale in New York — -Species and 

 Distribution, " by H. E. Hodgkiss and P. J. Parrott. 



THE PARASITES OF THE SAN JOS£ SCALE IN NEW YORK 



Hy H. E. Hodgkiss and P. J. Parrott 



(Abstract) 



Parasites of the San Jose Scale were numerous during 1913 in New 

 York. To determine the range and species of these insects, infested 

 wood was collected from unsprayed trees in the more important fruit 

 districts of the State. This was obtained from twenty towns repre- 

 senting thirteen counties. From the material we reared the following 

 species, — ProspalteUa perniciosi Tower, Aphelinus fuscipe?inis Howard, 

 Aphelinus diaspidis Howard, Signiphora nigrita Ashmead, and Peris- 

 sopterus pulchellus Howard. The last two species mentioned appear 

 to be of comparative unimportance. Taking the state as a whole our 

 breeding records for September and October 1913, indicate that 

 perniciosi was probably the most numerous species during that period. 

 Diaspidis was numerically greater in two counties while fuscipennis 

 ranked first in three counties. It should also be recorded that a count 

 of nearly 800 parasites collected at random showed that about one- 

 half of the specimens were perniciosi, one-third were diaspidis while 

 the remainder were fuscipennis. 



Considerable interest has lately centered on the efficiency of para- 

 sites to hold the scale in check. To determine the ratio of parasitism 

 numerical counts were made of the scales after the rearings of the 

 parasites were completed. Some twenty thousand individuals were 

 examined of which about thirty-five hundred contained exit holes of 

 the hymenopterons. The percentage of scales affected was variable 

 and on the average ranged between 12 per cent and 24 per cent for 

 the entire state. Locally the range was greater and the tabulations 

 based on wood collected at Geneva showed a difference of from to 



