AN INTERNAL. PARASITE OF THYSANOPTERA. 37 



appeared satisfied, the antennae were dropped downward, touchini^ the larva. The 

 abdomen was curved under the body and a long, slender, yellowish ovipontor extended 

 from near the anal end of the body. This was quickly thrust into the body of the 

 thrips larva, and as soon as the egg was deposited the ovipositor was withdrawn. 

 Genorally this was easily done, l)ut in a few cases a short struggle was necessary before 

 it could be accomplished. The ovipositor was usually inserted into the abdomen 

 near the anal end, but sometimes it is thrust into the side of the thorax. In one 

 instance, where the larva had been approached from in front, the ovipositor was 

 inserted into the front of the body. After the egg was deposited the i)arasite in some 

 instances would immediately select a new victim or she would rest while cleansing 

 her legs, antenna?, and body and then resume her quest. In other cases, after care- 

 fully examining a host larva she would leave it without attempting to oviposit. On 

 eome occasions the female was observed to deposit an egg in a larva and after leaving 

 it would shortly return to the same one and oviposit a second or even a third time. 

 In the majority of cases the larvye of IleUothrips fasdatus did not seem to be in the 

 least disturbed by this action. While the writer was engaged in observing oviposition 

 •he timed the parasite from its first touching of the host larvae with its antenme until 

 the ovipositor was finally withdrawn and in three cases this procedure occupied 20, 

 50, and 30 seconds each. One female was carefully watched and in 5 minutes ovipos- 

 ited in 4 different larvae and rejected two others after short examination. During the 

 second 5 minutes this female deposited 2 more eggs. Another female, recently 

 emerged, was placed in a vial with a large number of larvfe of this thrips at 3.15 p. m. 

 At 3.25 p. m. she had deposited her first egg and during the next hour, under the 

 constant observation of the writer, she deposited 20 eggs in 18 larv» in a period of 35 

 minutes, and 38 eggs in 36 larvae in 60 minutes. 



Ovi])osition in the larvae of Thrips tabaci was identical with that 

 in II. fasdatus, but the thrips larvae were more active and more easily 

 alarmed so that they either moved away or violently tlirew the tip 

 of the abdomen around. In such cases, the parasite retreated but 

 in a short time again approached the larva and in most cases after 

 two or three failures would eventually succeed m ovipositing in the 

 larvae. The same thing was noticed vni\\ the larva^ of Euthrips 

 tritici, but in both case? the parasite by returning to the attack 

 generally accomplished her purpose. The same parasite was often 

 placed with, one after another of these three species of thrips and 

 would oviposit in each one without appearing to notice the differ- 

 ence. In one case a parasite was observed trying to oviposit in a 

 dead thrips larva that was still more or less soft. StiU another 

 adult was observed attempting oviposition in a soft lump of dirt 

 in the vial. 



This parasite does not seem to prefer any particular size of larva, 

 as it has been seen to oviposit m all sizes, from larviie not over a day 

 or two old to larvae ready to change to prepupae. If, while examining 

 tlie leaf for thrips larvae, it engounters a larva fi'om in front, the para- 

 site generally moves around to the side and then oviposits in the region 

 of the thorax or the abdomen. 



