266 THE DIPLOPTERA. 



decreasing size of the remaining segments necessarily 

 brings their yellow rings into rather close juxta- 

 position. This insect is the Odynerus parietum^ a 

 very common species^ the female of which forms a nest 

 of earth in the holes of walls and similar situations, 

 for the reception of its youngs laying several eggs in 

 separate earthen cells^ each of which is stored with 

 caterpillars^ and according to some writers, also 

 with flies. It is probably to this species that Mr. 

 Westwood refers, in describing a singular instance of 

 instinct in an Odynerus. He says that it "provisions 

 its nest with the leaf-rolling larva of Tortrix [Argy- 

 Totoza) Bergmanniana'^ y which it dislodges by intro- 

 ducing its sting into the rolls of the leaves, imme- 

 diately running to the end of the roll in order to 

 ascertain whether the larva was endeavouring to 

 make its escape from its unknown enemy .^^ 



The habits of all the Solitary Wasps, in which of 

 course we only meet with males and perfect females, 

 appear to be very similar to those of the common 

 species just referred to, — they either form cavities, or 

 take possession of those already existing in walls, 

 palings, &c., line them with mud, divide them into a 

 suitable number of cells, and deposit an ^^^ in each 

 of these, together with the necessary supply of food 

 for the larva, in the shape usually of the larvae of 

 other insects. Sometimes, however, they have been 

 known to select a singular situation for the con- 

 struction of their nests, these having been found in the 

 folds of a piece of paper which had fallen down behind 

 some books, on the top of a book, and on the front 



* A species of Moth, the caterpillar of which rolls up the 

 leaves of roses. 



