COLOUR SENSE IN A KEYHOLE WASP. 93 



their larval skin for the last time and become a chrysalis. In 

 this paralysed condition they will live for a long time with but 

 little change. I have kept them for two months or more, and 

 they thus serve for food for the wasp grub while it grows to 

 maturity. It then assumes the pupal state and emerges later 

 on as a perfect insect. In the present case, which was brought 

 to my notice by Captain Aclandand Major Platt of Dorchester, 

 the latter gentleman had a cardboard box about 15 by 5 by 3in. 

 in size, containing 32 reels of variously coloured cottons with 

 a few silks, including six green, four red, three yellow, two 

 brown, one grey, four mauve and twelve blue of different 

 shades. The box was kept on a chest of drawers near a 

 window facing S.S.W., the window being almost always open, 

 and as the top of the box fitted badly, there was no difficulty 

 about the ingress of the wasp. The reels were used with a 

 sewing machine, which caused the paper at one end of the 

 reel to be removed and the other to be broken, thereby 

 allowing the wasp's entrance to the hole in the middle. The 

 reels were in any and all positions, as they were very frequently 

 turned over in looking for the special colour wanted at the 

 moment, so that it is extremely improbable that three reels of 

 the same colour would be so placed as to be specially 

 convenient for the wasp's attack. In the late autumn of 1919 

 Major Platt noticed that three of these reels had their holes 

 filled up with mud (cells); and one, with some light blue cotton 

 still on it, was sent to me by Captain Acland for the purpose 

 of identification. This I exhibited at the December Field 

 Club Meeting. Later on it was observed that all the three 

 reels which were tenanted by the wasps were of the same 

 colour and shade, light blue, shewing a striking and extra- 

 ordinary preference for that colour and shade, there being 

 only five or six light blue reels out of the whole 32. There 

 would probably be a little light in the box through the badly 

 fitting lid, which was often left partly open, as the box was 

 well filled up with reels, and without a little arrangement some 

 would project. I am not aware that anything is known about 

 the preference of these wasps for any particular colour, or 



