SOLITARY AND SOCIAL WASPS 



surrounded by a ring of cocoons. After a few cycles of this 

 sort the arrangement tends to get out of step, and any comb 

 in which all stages are found mixed together is known to be 

 an old one. 



The development from egg to adult takes about thirty 

 days ; the exact time depends partly on the temperature and 

 partly on the age of the nest. A comb which has the eggs, 

 grubs and cocoons irregularly arranged must be at least ten 

 weeks old. A cell which has been used before can always 

 be recognised under the microscope by the remains of the 

 thin silken lining which formed part of the cocoon, and by 

 the dried larval excreta which accumulate at the bottom of 

 the cell. 



A successful nest in the late summer may contain thou- 

 sands of cells and perhaps two or three thousand workers. 

 A nest of the common wasp, which I dug up in a field at 

 Slough on September n, 1935, contained a queen and 

 3,008 workers. ,It consisted of eight combs, with 11,299 cells 

 in all. The fifth and sixth combs were the largest, each with 

 about 2,188 cells. Nearly all the cells contained brood in 

 various stages, so that many more wasps, including young 

 queens and males, would have been produced later. 



No nest with more than one or two hundred workers can 

 be safely examined without destroying the wasps. This can 

 be done most conveniently with the dangerous poison 

 potassium cyanide : a piece as big as a walnut placed at the 

 entrance will rapidly kill every adult wasp. Carbon bisul- 

 phide and some other poisons are almost equally effective. 

 The Slough nest was not unusually large, and much bigger 

 ones, with up to ten thousand workers, are found in some 

 years. In such nests a great deal of food has to be brought 

 in, and large numbers of flies and other harmful insects are 

 consequently destroyed. Unfortunately, wasps are not very 



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