DIPLOPTERA WASPS EUMENIDAE 



73 





fossorial Hymenoptera), but complete evidence of this does not 



seem to be extant, and if it be so, the stinging does not 



completely deprive the caterpillars of the capacity of movement, 



for they possess the power of using their mandibles and of 



making strokes, or kicking with the posterior part of the body. 



It is clear that if the delicate egg of the Eumenes or the deli- 



cate larva that issues from it were placed in the midst of a 



mass of this kind, it would probably 



suffer destruction ; therefore, to 



prevent this, the egg is not placed 



among the caterpillars, but is sus- 



pended from the dome covering 



the nest by a delicate thread 



rivalling in fineness the web of the 



spider, and being above the mass 



of food it is safe. AVhen the 



young larva leaves the egg it still 



makes use of the shell as its habit- 



ation, and eats its first meals 



from the vantage-point of this 



Suspension; although the mass of FIG. 28. Nidification of solitary wasps: 



the food grows less by consumption, section **%"&. J> A > f - 



nerus remformis ; B, of Eumenes 



the little larva is Still enabled to arbustorum. a, The suspended egg 

 I -, i , i r> ,1 4.1 of the wasp ; b. the stored cater- 



reach it by the fact that the egg- pillars> fifa > AM) 

 shell splits up to a sort of ribbon, 



and thus adds to the length of the suspensory thread, of which it 

 is the terminal portion. Finally the heap of caterpillars shrinks 

 so much that it cannot be reached by the larva even with the 

 aid of the augmented length of the suspensory thread ; by this 

 time, however, the little creature has so much increased in size 

 and strength that it is able to take its place amongst the food 

 without danger of being crushed by the mass, and it afterwards 

 completes its metamorphosis in the usual manner. 



It is known that other species of Eumenes construct vase- 

 like nests ; E. imguiculata, however, according to an imperfect 

 account given by Ferris, makes with earth a closed nest of 

 irregular shape, containing three cells in one mass. The saliva 

 of these builders has the power of acting as a cement, and of 

 forming with the clay a very impenetrable material. One 

 species, E. coarctata, L. of this genus occurs in Britain. The clay 



