Colour Sense in a Ike^bole Wasp, 



(Odynerus parietinus, Linn.) 



By NELSON MOORE RICHARDSON, B.A. 



Read 17th February, 1920. 



HE little wasps belonging to the genus Odynerus, 

 which are the subject of this note, must be well 

 known to everyone, as they are very common and 

 much given to coming into houses, where they may 

 often be seen on the windows or elsewhere during the summer. 

 They are a good deal like an ordinary wasp in appearance, but 

 much smaller and slimmer. The nest of the species under 

 consideration (Odynerus parietinus, L., but until the perfect 

 insects emerged, it might have been one of three or four 

 species, which have similar nesting habits) is made in any 

 convenient hole, such as a keyhole, or, as in the present case, 

 the hole in a cotton reel, and consists of several cells, one above 

 the other. The cells are made of silk, with a thin coating of 

 mud; and in each is deposited an egg and some small cater- 

 pillars, generally smooth green ones. The caterpillars are first 

 stung by the parent wasp, the effect of which is to paralyse 

 them, so that they can only wriggle slightly. In fact they get 

 into the state which many larvae assume just before they cast 



