290 A BOOK OF INSECTS 



a section similar to that which is portrayed on Plate XL I. 

 We should notice the tunnel, leading from the outer 

 world, through which the busy workers hurry to and fro. 

 Between the walls of the cavity and the nest there is a 

 space, widened at intervals to form galleries for the con- 

 venience of those wasps whose duty it is to repair and 

 enlarge the outer cover. The only entrance to the nest 

 proper is at its lower extremity. Through this gate hurry 

 the workers laden with food and building materials; 

 others, issuing, carry dead grubs and the refuse of the 

 nest. A nest which is examined late in the season usually 

 consists of seven combs, hanging one from the other ; but 

 the cell structure of the first or upper comb is generally 

 cut away when the community becomes populous, so as 

 to form a commodious hall wherein the adult wasps con- 

 gregate at night and in wet weather. Apart from this the 

 paper cells are cleaned and used again and again for rear- 

 ing successive broods of grubs. 



We may imagine ourselves entering the nest and 

 mixing with the throng of workers. We shall realise at 

 once that we have come into a topsy-turvy realm, for if 

 we stand upon the surface of one comb and look vertically 

 upwards, we see into the cells of the comb next above. 

 Some of these contain eggs, others grubs in various stages 

 of growth, while still others are closed to the eye by caps 

 of spun silk. In these last the pupa? lie hidden. That 

 the wasps should have chosen this head-downward method 

 of rearing their young is very puzzling. The disadvan- 

 tages are many and obvious. The rule is that the 

 queen glues the egg to the side of the cell. When the 

 grub hatches, it remains at first with its tail in the egg- 

 shell, moving upon this pivot, and craning its head to the 

 mouth of the cell to receive food from the workers. But 

 as it grows, it must change its position in order to avail 



