28 MISCELLANEOUS PAPERS. 



incomplete; mesonotum without a median groove; scutellum without longitudinal 

 grooves; propodeum without a median carina; spiracles round ; submarginal vein very 

 short, marginal vein long, stigmal short, the knob almost subsessile; postmarginal vein 

 developed though not showing distinctly, as it is, as are the other veins, colorless; 

 marginal fringes of anterior wings almost two-thirds as long as the greatest width of the 

 wings. 



Female. — Length about 0.6 mm. Head and thorax black, the abdomen brown, 

 with a large basal flavous spot; head thin anterio-posteriorly, collapsing after death; 

 antennae testaceous, the pedicel longer than the two joints of the funicle combined; 

 second joint of the funicle longer than the first; hairs on antennae long; head and 

 thorax smooth, polished; legs including the coxae testaceous; wings hyaline, the veins 

 colorless. 



Male unknown. 



LIFE-HISTORY SUMMARY OF THE ORIGINAL HOST. 



{Heliothrips fasciatus Pergande.) 



HeliotJirips fasciatus Pergande, the original host of this parasite, 

 is found throughout the entire State of Cahfornia. In the vicinity 

 of Compton, during the months of July and August, the following 

 life-history notes were obtained. 



The eggs are laid in the leaves of the food plant and hatch in from 

 13 to 19 days. The larvas immediately begin to feed on the leaves 

 of the host plant, generally on the underside, but when crowded 

 appear to thrive on the upper surface of leaves as well. This stage 

 requires from 10 to 12 days, and as soon as the larvae are full grown, 

 most of them leave the plant to pupate in rubbish or cracks. The 

 prepupal and pupal stages together occupy from 7 to 12 days, making 

 the total length of the life cycle from 30 to 44 days. The insect is 

 thus exposed to the attack of the parasite during the larval stage 

 only, or for from 10 to 12 days. 



METHODS OF COLLECTING FOR EVIDENCE OF PARASITISM. 



The small size of both the host and the parasite makes it imperative 

 that special methods be adopted in the rearing of these insects. In 

 making collections for evidence of parasitism the bean leaves badly 

 infested by the host thrips were picked and brought into the labora- 

 tory in tin boxes. The thrips larvae were then removed with camels- 

 hair brushes and placed on freshly picked leaves of the food plant. 

 These were then placed in vials (100 mm. in length by 28 mm. in di- 

 ameter), which had been lined at the bottom with filter paper. (See 

 fig. 1, at left.) It was found that the filter paper absorbed the surplus 

 moisture and the material transformed better than in cases where the 

 filter paper was omitted. These vials were then tightly closed with 

 cotton plugs, labeled, and put into an outdoor insectary. Each 

 day the material was examined, and the larvae, when necessary, were 

 removed to fresh leaves by means of the brushes. As soon as full 



