INSECT NESTS SJOSTEDT. 343 



to work. We find among them simple combs with openings di- 

 rected downward, which are not made of wax but of vegetable ma- 

 terial finely pulverized and macerated by the secretions of the in- 

 sect's mouth. If we examine different wasps' nests carefully, we 

 note that some are elastic and resistant, while others are tender and 

 fragile, depending upon the material used by the insect. In the sec- 

 ond case, the substance consists of long wood fibers, and in the other, 

 of a different kind of vegetation. The fragile paper of the nests of 

 certain species is taken from the bark of various trees and has the 

 appearance of ribbons. 



The simplest form of nest is made by the Belonogaster wasps. 

 These large, somber, silent-flying wasps are found in the hot regions 

 of Africa. Their nests generally are made simply of cells fastened 

 together on top of a twig, without any envelope, although some spe- 

 cies are not contented with such rudimentary nests and have added 

 to them different methods of protection. We may cite the Charter- 

 gus chartarius, a species found in tropical America. Its nests (pi. 1, 

 fig. 2) are sometimes as much as half a meter long, and are composed 

 of a great number of stories connecting by a central opening. As the 

 colony grows a new story is built on the preceding one, the surround- 

 ing wall being torn down and reconstructed to inclose the new story. 



II. 



In all the cases that we have mentioned the nests have been built by 

 the adult insects to insure the protection of their young. But certain 

 larvae, which live a free and vagabond life, know how themselves to 

 prepare a shell for the chrysalis, which is, of course, defenseless. 

 I once had occasion to study the larvse of one of the processionary 

 caterpillars, Anaphe, in West Africa. They marched in a column up 

 the trunk of a tree to a branch where they constructed a great common 

 cocoon (pi. 2), consisting in part of the long hairs from their bodies; 

 inside this great envelope each larva surrounded itself with a cocoon 

 of silk, and in the silken cocoon it made a capsule of parchment- 

 like tissue which served as the last protection for the chrysalis. 

 Although in case of Anaphe the insects leave the nests without show- 

 ing any trace of their leaving, with Hypsoides the exit is effected 

 through a series of individual holes which make the abandoned nest 

 look like a sieve (pi. 1, fig. 1). 



In tropical regions one meets upon walls and stones, earthy nests 

 60 to 100 millimeters long, of an irregular, oval form, made by the 

 wasp, Sceliphron. Other nests of a rounder form are built on the 

 branches and trunks of trees by another wasp, Eumenes. These 

 nests are found in Africa, chiefly in inhabited regions. If we 

 closely examine these earthy structures which are apparently com- 



