296 Mr Warburton, Note on the solitary wasj), 



Note on the solitary wasp, Crabro cephalotes. By Cecil 

 Warbueton, M.A., Christ's College. 



[Read 10 November 1919.] 



Last summer a small colony of C. cephalotes took possession in 

 my garden of a log of elmwood which was kept as an example of 

 a woodpecker's nest. The entrance hole of the woodpecker was 

 there, and just below it the log had been sawn through so that the 

 internal cavity could be examined. 



The first advent of the wasps was not noticed, but in the first 

 week of August a wasp was observed entering the hole, and this 

 led to an investigation of the log, which presented signs of boring 

 in the half-decayed heart-wood. One of the wasps had attacked 

 the log from the top and its operations could be noted with more 

 or less exactness, but the others passed in and out by the wood- 

 pecker's hole, and it was impossible to recognise individuals or to 

 follow their work without constantly disturbing it by opening up 

 the log, with the risk of inaccurately replacing the two halves. 

 The log was nevertheless opened several times during the first half 

 of August, but it was then thought better to let the wasps finish 

 their work without further disturbance. 



That the wasps are not easily diverted from their labours the 

 following facts sufficiently demonstrate. The log was moved several 

 yards, to a spot more convenient for observation. The wasp 

 working on the top (hereafter referred to as wasp No. 1) was 

 captured in a glass tube and examined for identification, but on 

 being liberated continued working as before. Close observation, 

 with a hand lens, did not deter this wasp from entering its burrow 

 without hesitation in the course of its operations, nor were the 

 other wasps disconcerted by the removal of the lid on several 

 occasions at an early stage of their work. As a rule no attention 

 was paid to anyone sitting silently near the log, but it must be 

 recorded that on one occasion a wasp returning with a fly appar- 

 ently objected to the dress — light with dark spots — of a lady sitting 

 near at hand, and after a close investigation from many points of 

 view, retired instead of entering the log. To ascertain if wasp No. 1 

 were at home or not I was in the habit of placing a stout straw in 

 its burrow — protruding an inch or more. One would have thought 

 that on returning home and finding such an object impeding its 

 entrance the insect would manifest some perturbation and either 

 refuse to enter or take some measures to remove the obstacle. It 

 did nothing of the kind, but absolutely disregarded the straw, 

 pushing past it even when laden with a fly. It was several times 



