544 HYMENOPTERA 



shut up in the cell of the Chalicodoma, at whose expense the 

 Stelis also lives parasitically. The Monodontomerus bores a hole 

 through the masonry of the bee and deposits its eggs in the ce] 

 after the fashion of the Zeueospis ; one bee larva is, howeverj 

 sufficient food for several individuals of the young of this smaller' 

 parasite. There is no hypermetamorphosis, the early larval 

 condition resembling the later. This Insect attacks not only 

 Chalicodoma and Stelis, as already mentioned, but also other bees : 

 and a single larva of some of the larger kinds will afford sufficient 

 food for fifty young of the Monodontomerus. They feed on the 

 bee larva, as the Leucospis does, without wounding it. This fly 

 has the power of recognising what is suitable provender for its 

 young by the use of the antennae, even when the conditions are 

 so changed that it is clear the sense of sight has nothing to do 

 with the recognition. Fabre relates that he had extracted a 

 number of the bee larvae from their cells of masonry, and that 

 as they were lying on his table enclosed in their cocoons, the 

 Monodontomerus recognised the latter as containing the desired 

 provender for its young by examining them with its antennae : 

 after which, without hesitation, the Monodontomerus pierced the 

 cocoon with its ovipositor and deposited the eggs in a suitable 

 position. This observation, together with those made on Leucospis, 

 seem to indicate that it is neither by sight nor smell that these 

 Insects discover the desired object, but by some sense we do not 

 understand, though its seat is clearly in the antennae of the 

 Insect. 



Newport discovered a Monodontomerus, which he described 

 as M. nitidus} in the cells of the bee AnthopJiora retusa, and 

 demonstrated that the alimentary canal, as is usual in Petiolate 

 Hymenoptera, is closed behind until the Insect is about to enter 

 the pupal state, when it becomes perforated and faecal matters 

 are for the first time passed from it. " These matters were com- 

 posed of the refuse of digestion and of epithelial cells accumulated 

 during the period of feeding, and retained in the digestive sac 

 until the period of its perforation. In this way the food and 

 abode of the Insects are maintained pure and uncontaminated, 

 and the digestive apparatus is completed, and the refuse of 

 nutrition ejected only when the whole of the food has been 

 consumed." 



^ Tr. Linn. Soc. xxi. 1855, p. 67, 



