AN INTERNAL PARASITE OF THYSANOPTERA. 43 



experiments also failed to give an}^ further results, due no doubt to 

 the Ihictuating teni|)erature of the buildmg where the experiments 

 were conducted. 



MISCELLANEOUS OBSERVATIONS. 



Larvae of Tnchothrips n. sp. were confined with the parasite, but 

 whenever the parasite came into contact with the larvae it at once 

 moved away and ujk)1i no occasion did it attempt oviposition. The 

 refueal of the parasite to oviposit was no doubt due to the fact that 

 this Ci|Tips was much larger, of an advanced stage, and with a tougher 

 skin. ^ 



While observuig the oviposition of the parasite in thrips larvae, 

 one was observed to come mto contact with a small red spider 

 (Tetranychus 9). The parasite immediately stopped, examined 

 the mite, and then bent under the abdomen and oviposited m it. 

 Undoubtedly this was a case of wasted energy, as the body of the 

 mite was entirely too small to nourish the larva of the parasite. 



Young of Triphleps insidiosus Say were placed m a vial with the 

 parasite, but no attempt to oviposit was observed. In most cases 

 the young bugs moved so rapidly that the parasite could not get 

 near enough to touch them. 



In one experiment Mr. Graf placed very young cabbage aphides 

 (Aphis hrassicsR L.) in the vial with the thrips parasite, but it refused 

 to oviposit in tliem. 



SUMMARY OP EXPERIMENTS TO DETERMINE HOST RELATIONS. 



To briefly summarize the results of the foregoing experunents, 

 this parasite has been reared from Heliothrips fasciatus Pergande, 

 Thrips tabaci Lindeman, and Euthrips tritici Fitch. It has also 

 been observed to oviposit m larvae of Heliothrips hsemorrhoidalis 

 Bouche and Heliothrips femoralis Renter, but without results at the 

 present wi'iting. Upon one occasion, as noted above, it oviposited 

 in a red si)ider, also without results. Although given tlie oppor- 

 tunity it refused even to attempt ovij)osition in Trichothrips n. sp., 

 Triphleps insidiosus, or Aphis hrassicse. 



LENGTH OF LIFE IN CONFINEMENT. 



Owmg to the artificial conditions under which this insect was 

 studied, the normal length of life must have been greatly curtailed. 

 However, adults were often noted in active oviposition for from 3 

 to 5 days and one was recorded that oviposited on the first and 

 eighth days of its confinement. Adults have been kept alive in the 

 tubes for a period of 10 days. In another case adults were found 

 alive in a sliipment of material that was in the mail for 2 days. This 

 insect probably has quite an extended length of life under natural 



