AN INTERNAL PAKASITE OF TIIYSANOPTERA. 



49 



of the host larvae made at Garden Grove and in Los Angeles failed to 

 show parasitism, but probably more extensive collections would have 

 revealed the pi'esence of this insect in both places. Compton, which 

 is near the coast, has a much cooler climate than Pucnte, wliich is 

 more inland, so that tliis insect appears to thrive along the coast and 

 also in the drier antl hotter interior valleys. 



PERCENTAGE OF PARASITISM IN DIFFERENT LOCALITIES. 



The hosts of this i)arasite are such delicate insects that in all rearing 

 work many have died from the artilicial conditions in the vials. 

 Therefore it is impos- j^ 

 sible to give the exact 45 

 percentages of the 

 number of thi'ips par- 

 asitized by this insect 

 or the number of nor- 

 mal forms. Never- 

 theless some idea may 

 be obtained of the 

 work this insect is 

 capable of doing to 

 check its host, Helio- 

 tliripsfasicatus, in Los 

 Angeles County, Cal. 

 at Compton for 1911. 



Table IX. — Ferccniufje 0/ parasitism of Ileliothrips fasciatus, Compton, Cal., 1910-11. 



.40 

 '^35 

 \30 



28 2S 30 3/ 3Z 33 34 35^ 36 J7 J$ 39 ■W 4J 42 43 44 



Fig. 10.— Diaf,'ram illustrating total number of days in (ho life cycle of 

 Thripoctcnus russdli; summary of all rearing experiments. (Original.) 



Table IX gives the percentage of parasitism 



1 About. 



2 Not determined. 



