210 THE BOOK OF NATURE STUDY 



entrance, and then serve as food for the grubs of small flies which 

 act as scavengers. The eggs of these flies are laid upon the outer 

 wrappings, and may there be seen as small white specks. In 

 the later part of summer, combs containing " royal " cells of 

 extra large size are added below the rest. In these cells the 

 young queens of the next generation are reared. At this season 

 the population is at its maximum, amounting to several thousands, 

 indeed so many as 60,000 individuals may be reared in one nest 

 during a single season ; hence the supplies of food brought into 

 the nest are abundant, and it seems that it is the quantity rather 

 than the quality of the food which determines whether any one 

 fertilised egg shall give rise to a " queen " or merely to a worker. 

 It not infrequently happens that some of the larger, better fed 

 workers lay eggs. These eggs, however, are not fertilised, for 

 the workers are incapable of being impregnated, and produce, 

 as do the unfertilised eggs deposited by the " queen," drones 

 only. 



At the end of the season, as food supplies become scarce, 

 many of the grubs are devoured by the hungry workers. Eventu- 

 ally the whole establishment falls a prey to mice, earwigs, beetles, 

 and many other creatures, and disappears. The whole duration of 

 its existence is but a few months, namely, from April to November 

 at the longest. From what has been stated regarding the diet 

 of wasps, it will be seen that though they inflict much damage 

 upon fruit crops, yet they are very useful as scavengers, and in 

 destroying numerous insects that are harmful to horticulture. 



The seven species of British wasps (Vespa) may be distin- 

 guished by the following characters : 



1. The Hornet (Vespa crabro) : thorax reddish brown, not 

 black. A much larger insect than any of the others. Nest 

 built in hollow trees, outhouses, or occasionally in banks, but 

 near the surface. 



2. Vespa vulgaris : thorax black and yellow ; lateral yellow 

 stripe on first thoracic segment straight and parallel-sided. Face 

 short, base of mandibles almost touching eyes. Scape of 

 antenna of ? (queen) and $ (worker) black. Yellow blotch 

 in concavity of eyes hollowed out. Median black line on 

 clypeus of variable size, but not flanked by two other black 



