106 THE SOLITARY WASPS. 



by tlie second or tliird day and by the fourth or fifth were all 

 dry and brown. The exception to the rule was a very lively lit- 

 tle aphis found in a closed nest with about forty dead ones. We 

 have no doubt that they are often alive when first taken in, from 

 the fact that while watching the action of the wasps in the bot- 

 tle we noticed that they not infrequently left the aphides al- 

 most uninjured. 



In four of the nests we found the egg, which in one instance 

 was on the under side of the body of the aphis, while in the 

 other cases it was placed on the dorsum. Perhaps one of the 

 eggs was laid by a parasite and this was the reason of the dif- 

 ference in position. 



Only two of the eggs hatched. The first of these (jS^o. 23) 

 was taien from a nest which had been closed up at three in the 

 afternoon on July twenty-second. At nine in the morning of 

 July twenty-fourth we found that it had hatched, and it seemed 

 to be a few hours old. The egg stage, then, probably lasts 

 about thirty-six hours, although we judge that it may in some 

 instances be less from the case of another wasp, No. 24. This 

 nest was also closed up by the wasp on July twenty-second, and 

 we dug it up on the afternoon of the same day. The larva, 

 however, hatched at nine in the morning of July twenty-third, 

 nearly a day sooner than the one in nest ]^o. 23. This, to be 

 sure, may have been due, not to a more rapid development of 

 the egg, but to its having been laid earlier, perhaps shortly after 

 the provisioning of the nest was begun, while in the other case 

 it may have been laid after the aphides had all been carried ,in. 

 "We know that in certain other wasps (Pelopaeus) there is just 

 such a variation as this in the point of time at which the egg is 

 laid. 



These two wasplings lived through the six days of their larval 

 life. They ate the whole aphis, leaving no debris. At the end 

 of that time one of them died and the other spun its cocoon. In 

 the tube with this later larva we discovered, on the seventh day 

 after the nest was taken up, a second smaller larva which was 

 also eating the aphides. This one, which was probably the 



