542 HYMENOPTERA CHAP. 



cospis larva in a cell. Even in cells where he had observed 

 more than one act of oviposition, and which he had marked at 

 the time, only one larva existed. This induced him to think 

 that it was possible that no egg was deposited by the Leucospis 

 at the second penetration. He accordingly examined cells soon 

 after the eggs were laid, and thus discovered some that contained 

 more than one egg, indeed in one cell he observed no less than 

 five eggs suspended from the cocoon of the Chalicodoma ; he was 

 also able to demonstrate that eggs were actually deposited in some 

 cells that contained no means of support for the larva. How then 

 could these two facts be reconciled four or five eggs deposited in 

 a cell, only one larva present afterwards ? It is of course impos- 

 sible to observe the operations of a larva shrouded in the obscurity 

 of a cell formed of masonry, so he transferred some bee larvae 

 with their destructive companions to glass tubes, in which he was 

 able to note what took place. He found that the egg deposited 

 by the Leucospis hatches and produces a very peculiar larva, 

 having little resemblance to the Leucospis larva that he had found 

 eating the Chalicodoma larva. The primary larva (Fig. 357, B) 

 of the Leucospis is an arched worm, moderately deeply segmented, 

 a millimetre or a little more in length, with a remarkably large 

 and abruptly-defined head. The body bears 

 erect setae, the most remarkable of which 

 are a pair on the ventral aspect of each of 

 the segments, each of these ventral setae 

 being borne on a small conical prominence. 

 These prominences and setae serve as ambu- 

 latory organs, and are supplemented in their 

 function by a protuberance at the posterior 

 extremity. The little creature has consider- 



FIG 357 Leucos 7s i as a ^ e P owers f locomotion ; it moves, after 



A, Egg; B, primary, the fashion of many other larvae, by con- 



(AfterTabreY ^'^ tractin g an( * arching the body so as to bring 



the posterior part nearer to the anterior ; 



then fixing the hinder part, the anterior is extended and fixed, the 

 posterior being again brought nearer to the front. The Leucospis 

 larva when hatched does not at once attack the bee larva which is 

 to be its future food, but every few hours makes excursions over 

 its surface, and even explores the walls of the cell ; returning, 

 however, always to the cocoon for repose. The object of these 



