58 Psyche [April 



asite (No. 1) which went through the preHminary motions of ovi- 

 position, but before it had completed the action another (No. 2) 

 ran up and pierced the thrips with its ovipositor. After remaining 

 in this position some minutes its apphed its mouth to the puncture 

 and sucked the wound for about the same length of time. Mean- 

 while No. 1 repeatedly brought its abdomen forward as if to ovi- 

 posit, but failed to do so. Both insects immediately afterwards 

 deposited something on the wall of the test tube, which may have 

 been merely excrement, though in the case of No. 1 it was shaped 

 very like the usual parasitic egg. 



Subsequently, numbers of adults and pupse of the Thripodenus 

 were obtained, and the process of oviposition was frequently 

 witnessed. The thrips and parasites (one individual of each, as 

 a rule) were placed on a glass side within a ring of paraffin, and 

 covered with a cover-slip. Under these unnatural conditions the 

 behavior of the parasites was somewhat capricious. Their first 

 action was almost invariably a systematic examination of their 

 prison, out of which, if there was the smallest space between the 

 wax and the cover they usually succeeded in forcing their way. 

 After these efforts had been brought to a conclusion they might 

 or might not show some interest in the thrips. Often they re- 

 mained with their antennse applied to the bodies of the larvse, 

 without attempting to oviposit. Under such conditions any slight 

 movement on the part of the thrips was likely to stimulate the 

 parasites to action. If they met with the thrips at an unfavorable 

 angle they seldom rectified their position, but let it go. The 

 thrips also showed some variation in their receptions of the at- 

 tack. They were generally rather quiescent, but sometimes 

 crawled about rapidly in their endeavor to escape. This was 

 usually successful, especially if done just as oviposition commenced, 

 but occasionally a more persistent parasite followed its prey, 

 sidling along to the best of its ability, and still holding on when 

 dragged head-long, or circumvented its victim by mounting on 

 its back. Sometimes the thrips, particularly the pupal forms, 

 protected themselves by violently contorting the tips of their 

 abdomen, and in one case one of them was seen to excrete a drop 

 of brownish fluid on the wings of the Thripoctenus. 



Oviposition, when successful, usually required ten or fifteen 

 minutes, and a half-hour was not uncommon. After this there was 



