766 



CLASS IV. INSECTA. 



she lays eggs which only give rise to drones ; the same is the case with 

 the fertilized queen in her old age when the contents of the recepta- 

 culum seminis are exhausted. Workers may also lay eggs which 

 develop into drones ; the larvae destined to become workers may, 

 if the food-supply at an early stage be abundant, become queens. 

 A hive may number as many as twenty to thirty thousand indi- 

 viduals, of which the drones do not form more than one per cent. 

 The following three families comprise the true Wasps. They are 

 sometimes classed together in a group, the Diploptera, characterized by the 

 anterior wings being longitudinally plicate in repose, the pronotum 

 reaching to the tegulae, and the posterior tarsi not being modified for 

 industrial purposes. 



Fam. 17. Eumenidae. Solitary wasps. Tarsal claws toothed or bifid ; 

 one spur only on the second pair of tibiae ; no workers and no communities. 

 A diverse group of some eight hundred species, sixteen of which occur 



in Britain. 

 Eumenes c o n - 

 structs a clay- 

 cell and stores 

 it with cater- 

 pillars, perhaps 

 partially para- 

 lysed by her 

 sting. Odynerus 

 uses hollows in 

 walls, wood, etc. 

 R h y g c hi um 

 forms cells in 

 pi ant -stems. 



Fam. 18. 

 Vespidae. Tar- 

 s a 1 claws 

 simple ; two 

 spurs on the 



second pair of tibiae ; workers present ; they live in communities in papery 

 nests. Wasps' nests are built of small vegetable fragments, often taken 

 from decayed wood, which are chewed up by the mandibles till they 

 become almost like coarse paper. The combs are usually in layers, each 

 hanging by little pillars from the layer above, and the whole surrounded 

 by an outer envelope. The workers, which are not structurally differ- 

 ent from the queens (perfect females), may occasionally lay eggs which 

 are probably fertilized. The colonies are annual, existing for 

 the summer only. In the autumn all die, with the exception of 

 a few fertilized females, which creep into crevices of trees or 

 under stones, and hibernate throughout the winter. In the spring the 

 female emerges and commences to build a nest. As soon as two or three 

 cells are finished the female lays an egg in each, and when the white 

 apodous grubs hatch out they have to be fed, whilst at the same time the 

 mother is widening and deepening their cells and adding others. 



The larval stage lasts about two weeks, and then the grubs cease to 

 eat and turn to pupae in their cells. The imago emerges in ten days, 

 and sets to work to enlarge the nest. As soon as the perfect insect vacates 

 its cell, this is cleaned out and another egg is deposited in it. 



FIG. 498. Odynerus antilope ? . Britain. From Sharp. 



