46O Scientific Intelligence, [Juke 



the males than the females. Linneus drew a distinction between 

 the hornets (V Crabro) and the true wasps, founded on these marks, 

 which cannot be considered as decisive, because they vary in different 

 individuals. 



5. The tree wasp has more black upon the body generally than the 

 other species. 



6. The tree wasp is rather larger. 7« The organs of generation 

 in the males of the two species vary considerably. 8. The abdomen 

 in each species contains the same number of rings, viz. six in the 

 females and neuters, and seven in the males. 



Mr. Bigge states some interesting facts in illustration of the natural 

 history of both species. Societies of wasps, as of bees, consist of three 

 different classes of inhabitants, males, females, and neuters. The 

 females, which are much larger than the others, are the large breed- 

 ing wasps which appear in the spring. The neuters, or imperfectly 

 developed females, are the common wasps which infest our houses and 

 gardens, and form the majority of the colony. The males, about the 

 size of the neuters, have longer antennae, a more slender form, and 

 are destitute of a sting. The females, which alone survive the winter, 

 early in the spring, having fixed on a suitable place for a nest, form a 

 few cells, in which they lay the eggs of neuters only. Each nest is 

 the work of a single female. The nests are often suspended from the 

 beam of a shed, from the eaves of a house, from the branch of a young 

 tree, or in a thorn hedge. 



Mr.Bigge has observed them in the Scotch fir, elm, and beech, 

 very frequently in larch trees, and still more so in goosberry bushes, 

 but never in the silver fir, as stated by Mr. Rennie.* 



The nest consists of from ten to sixteen layers of a paper like 

 substance, procured principally from fir wood, and disposed one over 

 the other in such a manner that each sheet barely touches the next. 

 This structure enables it to resist the heaviest rains. In its earliest 

 state it does not exceed an inch in diameter, and contains five or six 

 cells only. 



It is formed of two semicircular layers of the paper, the upper one 

 projecting a little over the other, so as to shoot off the rain, a hole 

 being left at the bottom large enough to admit the female wasp. As 

 soon as the first workers quit their cells they begin the task of en- 

 larging the nest, and of adding fresh layers of cells, in which the 

 female immediately deposits more eggs. Mr. Bigge states that the 

 nest is enlarged from one inch to twelve in diameter, and considers 

 that Leach is in error when he affirms that wasps build two nests 

 in the year. 



Is not the loose structure of the external covering intended to 

 facilitate its expansion ? 



The egg is hatched in eight days, and then assumes the form of a 

 grub. It is then fed by the female for thirteen or fourteen days, 

 when the grub covers the month of its cell with a silky substance. 

 It remains in this state for nine days, and then eats its way through 



* I have frequently observed nests situated on wild rose bushes (Rosa tomen- 

 tosa and canina,) in Scotland. The choice of these slirubs by the wasps is proba- 

 bly to be ascribed to the facilities which they afford for obtaining food. — Eon. 



