Insects. 



6647 



to their position in the nest and to the immediate object for which 

 they are designed ; the upper part of the case, for instance, is made 

 of a close, compact set of cells, into which any roots or stones are 

 worked ; while the sides are made in longer channels, as being less 

 liable to pressure, and sustaining less traction. 



In a nest of V. germanica which I had under observation, where 

 the object of the work was merely to close in a large hole which I had 

 cut in the wall of the nest, I thought that the cells were wider and 

 longer, and the wall altogether much slighter, than when any more 

 substantial enemy than light had to be excluded. These wasps 

 worked in the same way as V. britannica, and used the same mate- 

 rials, only, being larger, they got on faster. When making the shelly 

 patches which closed in the cells or channels of the wall, they worked 

 indifferently to the right or left, but always from without inwards, 

 forming an irregular spiral, which tended towards a little hole, just 

 big enough for the passage of the jaw of the wasp which put the 

 finishing stroke to the work. 



Reaumur, speaking of ground-wasps and hornets (' Memoires pour 

 l'Histoire des Insectes,' vi. p. 226), says that the nest remains open 

 at the bottom till it has attained its full size. From my own observa- 

 tions of nests of V. britannica and V. germanica, of all sizes, I 

 should say that the nest is always closed at the bottom except at 

 quite the earliest period. No doubt this is effected at a great 

 expense of labour, the walls having to be altered continually; but 

 economy of labour is no object with wasps, which, like the other 

 Hymenoptera, seem to know no rest but sleep, and, whether in the 

 way of construction or destruction, must always be doing something. 



Much perplexity has arisen from the different forms which wasps' 

 nests assume at different periods. At an early period there is no 

 specific mark to distinguish the nests of V. germanica and V. britan- 

 nica, for they are both alike formed of overlapping sheets and open 

 at the bottom. It is only in the cellular structure of the walls that 

 specific differences appear. I do not know the form of the nest of 

 V. vulgaris through all its stages, but only as the perfect nest, when 

 it resembles the structure of V. germanica diminished in all its parts. 

 Hornets do not seem to form the case of their nests on any uniform 

 plan, but rather to seek such extraneous protection as may obviate 

 the necessity of making any case at all, the numbers beiug fortu- 

 nately fewer in the colonies of this species than in the smaller 

 Vespidae, and the necessity of finding something to do being conse- 

 quently not so pressing. 



