AN INTERNAL PARASITE OF THYSANOPTERA. 



29 



grown the thrips larva; either pushed in between the vial and edge of 

 the cotton plug or in between the filter paper and the vial, in order 

 to pupate in protected places. 



Because of this habit it was very easy to determine parasitism and 

 the amount of material affected. It was found that many of the 

 smaller thrips larvae died before completing their growth, but tliis 

 mortality, fortunately, did not retard the investigation. 



When it was desirable to discover if material was parasitized or 

 to get adult parasites, the leaves infested with thrips larvae were put 

 mto small wooden boxes with holes bored in the sides for glass tubes. 



Fig. 1.— Vials used for the study of thrips parasites. (Original.) 



(See fig. 2.) These openings were kept closed until the thrips larvae 

 had all changed, and then the tubes were put in. The parasites upon 

 emerging immediately sought the light and were readily removed 

 from the tubes. 



METHODS OF REARING PARASITES FOR LIFE-HISTORY STUDY. 



In studying the life history and habits of this parasite, use was 

 made of the large vials described aboA'e. In this case, however, 

 the filter paj)er was left out of the tubes until after the parasite 

 had oviposited in its host. (See fig. 1, at right.) Whenever adults of 



26003°— 12 2 



