DIPLOPTERA WASPS — EUMENIDAE 



7. 



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. When 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 

 the food grows less by consumption, 

 the little larva is still enabled to 

 reach it by the fact that the egg- 

 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 l^eing crushed by the mass, and it afterwards 

 completes its metamorphosis in the usual maimer. 



It is known that other species of Uumenes construct vase- 

 like nests ; U. tinguiculata, however, according to an imperfect 

 account given by Perris, 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, K coarctata, L. of this genus occurs in Britain. The clay 



Fig. 28. — Nidification of solitary wasps : 

 section through nest, A, of Od)/- 

 nerus renif<yrmis ; B, of Eumenes 

 arbustorum. a, The suspended egg 

 of the wasp ; 6, the stored cater- 

 pillars. (After Andre.) 



