CHRYSIDIDAE 



they love the hot sunshine, and are difficult of capture. Though 

 not anywhere numerous in species, they are found in most parts 

 of the world. In Britain we have about twenty species. They 

 usually frequent old wood or masonry, in which the nests of 

 Aculeate Hymenoptera exist, or fly rapidly to and fro about the 

 banks of earth where bees nest. Dr. Chapman has observed the 

 habits of some of our British species. 1 He noticed Clirysis 

 iijiiita nying about the cell of Odynerus parietum, a solitary 

 wasp that provisions its nest with caterpillars; in this cell the 

 (. '// i't/sis deposited an egg, and in less than an hour the wasp had 

 sealed the cell. Two days afterwards this was opened and was 

 found to contain a larva of Clirysis a quarter of an inch long, as 

 well as the Lepidopterous larvae stored up by the wasp, but there 

 was no trace of egg or young of the wasp. Six days after the 

 egg was laid the Chrysis had eaten all the food and was full- 

 grown, having moulted three or four times. Afterwards it formed 

 a cocoon in which to complete its metamorphosis. It is, however, 

 more usual for the species of Chrysis to live on the larva of the 

 wasp and not on the food ; indeed, it has recently been positively 

 stated that Chrysis never eats the food in the wasp's cell, but 

 there is no ground whatever for rejecting the evidence of so care- 

 ful an observer as Dr. Chapman. According to M. du Buys- 

 son the larva of Clirysis will not eat the lepidopterous larvae, 

 but will die in their midst .if the Odynerus larva does not de- 

 velop ; but this observation probably relates only to such species 

 as habitually live on Odynerus itself. The mother-wasp of 

 Chrysis bidentata searches for a cell of Odynerus spinipes that has 

 not been properly closed, and that contains a full-grown larva of 

 that wasp enclosed in its cocoon. Having succeeded in its search 

 the Chrysis deposits several eggs from six to ten ; for some 

 reason that is not apparent all but one of these eggs fail to pro- 

 duce young ; in two or three days this one hatches, the others 

 shrivelling up. The young Chrysis larva seizes with its mouth 

 a fold of the skin of the helpless larva of the Odynerus, and 

 sucks it without inflicting any visible wound. In about eleven 

 days the Clirysis has changed its skin four times, has consumed 

 all the larva and is full-fed ; it spins its own cocoon inside that 

 of its victim, and remains therein till the following spring, 

 when it changes to a pupa, and in less than three weeks there- 



1 Enf. Mag. vi. 1869, p. 153. 



