XVIII A PARASITE— THE COCOON 24; 



The Bembex is not the only victim of these 

 parasites : the burrows of one and all of the mining 

 Hymenoptera are invaded by Tachinids, especially 

 by the Miltogramma. Various observers — notably 

 Lepeletier de Saint Fargeau — have spoken of the 

 manoeuvres of these impudent Diptera ; but as far as 

 I know none have perceived the very curious case 

 of parasitism at the expense of the Bembex — very 

 curious, because the conditions are quite different. 

 Nests of other Fossors are stored beforehand, and the 

 Miltogramma drops an egg on the prey just as it is 

 being carried in. The provender stored and her egg 

 laid, the Hymenopteron closes up the cell where 

 thenceforward live the legitimate larva and the 

 strangers, unvisited in their prison. Thus, the 

 robbery committed by the parasite is unknown to 

 the mother, and must consequently remain un- 

 punished. 



With the Bembex it is quite otherwise. The 

 mother constantly returns during the fortnight that 

 she is bringing up the larva ; she knows that her 

 offspring is living among numerous intruders, who 

 appropriate the greater part of the food ; every time 

 that she brings provender she touches and feels at 

 the bottom of her den these detestable guests, who, 

 far from contenting themselves with remains, seize 

 what is best. She must perceive, however small her 

 powers of arithmetic may be, that twelve are more 

 than one ; besides, she would discover this from the 

 disproportion between the consumption of food and 

 her means of hunting, and yet, instead of seizing 

 these bold intruders and bundling them out, she 

 serenely tolerates them. Tolerates ! Why, she 



