Insects. 



8791 



the larvae descend the tree, and get into the crevices in the trunk, or 

 amid the moss about the root, and there spin up in a most singular 

 cocoon ; this is made up of minute meshes formed by coarse threads, 

 and is transparent, so that the larva may be seen lying within the 

 cocoon ; the case itself may most aptly be compared to a tanned 

 fishing-net (fig. 4). According to Klug these little nets are found in 

 great numbers in the midst of the decayed parts of old willows. 

 What purpose is served by the singular structure of the cocoon is to 

 me an enigma; the hypothesis put forward by Frisch, namely, that 

 the openings serve to let out the redundant secretion of the larva, is 

 certainly untenable. The young insect remains in this cocoon until 

 May of the following year, in exceptional cases for two years, having 

 changed therein to a pupa in the middle of April. 



In consequence of the transparent structure of the case in this spe- 

 cies, the state of activity of larvae, even during the winter, can be well 

 observed ; on being touched it jerks the abdomen smartly round. In 

 order to get out of the cocoon the imago, by means of its large man- 

 dibles, gnaws a wide opening in the net-work. The sexes of the per- 

 fect insect are so differently coloured that earlier entomologists have 

 regarded the male and the female as distinct species. Both are rather 

 more than two centimetres long ; black, with a metallic lustre on the 

 head and thorax, these divisions of the body being, especially in the 

 male, covered with long gray hairs. The antennae have five joints, 

 the last being clavate and coloured red ; the four lower ones are 

 black. The upper lip, — which in the male is very large, rounded and 

 somewhat curved, — as also the clypeus, are white; the jaws are very 

 deep brown. The abdomen is black in the male, with gray hairs at 

 the t>ase ; the ventral surface, as also the anus, are ferruginous ; in the 

 female the abdomen is also black, but destitute of hairs ; the third 

 and fourth segirients have two white triangular spots on the sides, and 

 the succeeding segments are bordered with white ; the belly is 

 yellowish white, with narrow bluish black diagonal lines, and two lon- 

 gitudinal lines at the sides. The wings are glassy, with a brown 

 border, and a brownish spot before the stigma ; the nervures, as well 

 the stigma, are deep brown. The legs are very hairy in the male, less 

 so in the female ; in both sexes the coxae and femora are bluish black ; 

 tibiae and tarsi ferruginous. The posterior femora have a little tooth 

 at the knee. 



The antennae are somewhat longer in the male than in the female. 

 The labrum (fig. 9) is broad, slightly emarginate, and rounded ante- 

 riorly, narrower at the base, subtranslucent, and having but few hairs. 



