CH. V] WASPS 159 



It emerges as a perfect beetle a day or two after the 

 wasps in the surrounding cells. The cells of infected 

 specimens at first appear whiter than the rest owing to 

 the glistening white Rhipiphorus larva shining through 

 the silk cap. Later, when emergence is approaching, 

 they appear blackish or reddish as opposed to the 

 greenish tint of those occupied by wasps. From the 

 relative positions of the host and parasite it will be 

 evident that whereas a wasp-grub always faces towards 

 the centre of the comb, the beetle-grub faces towards 

 the circumference. 



The species of British Wasps (Vespidw). It has 

 already been pointed out in what particulars the true 

 social wasps differ from their immediate allies and other 

 insects with which they are at all likely to be confused. 

 The genital armature of the drones furnishes useful features 

 in the determination of species. This apparatus consists 

 of two pairs of forceps. The outer, or stipites, spring from 

 a basal ring, the cardo ; the inner lie between the stipites 

 and are called the sagittce. Below are given the diagnostic 

 characters of our seven British species. 



1. Vespa crabro, the Hornet: thorax reddish brown. May be 

 known by its great size, though " queen " wasps are often 

 mistaken for Hornets: the colour of the thorax is a sure 

 guide. Nests in hollow trees, outhouses or less frequently 

 in banks, in which case the nest is always very near the 

 surface. 



2. Vespa vulgaris : thorax black and yellow ; face short, i.e. no, 

 or very little, interval between eyes and base of mandibles ; 

 abdomen yellow and black, markings sharply defined ; lateral 

 yellow stripe on pronotum straight- and parallel-sided. 

 $ decidedly hairy. 1st joint (scape) of antenna of with 



