HYMENOPTERA. TEREBRANTIA. 165 



construct a home closely resembling that of many cater- 

 pillars. 



Others again, like the Clothes-moth and other case- 

 bearing caterpillars, form a little spiral case in which 

 they move and eat as safely as a snail in his shell. These 

 cases strongly resemble some made by the larvae of some 

 Caddis-worms. 



These solitary cells are not the only dwellings formed 

 by Tenthredo larvae ; some of the social species con- 

 struct large silken tents, and it is not an uncommon 

 thing to see a whole bush, or even a large portion of a 

 hedge, almost covered with these silken webs, every twig 

 denuded of its leaves and bound to those around it by 

 innumerable little cables. 



Some species have a curious property (which, however, 

 is not confined to these insects) of emitting a fluid 

 either from the mouth or from openings in the sides, 

 which in some cases has an extremely disagreeable 

 odour. 



The larva of one species, Selandria cerasi, common 

 on our pear, plum, and cherry trees, appears to be always 

 enveloped in a dark slimy secretion, which so covers the 

 insect as entirely to conceal it ; in the words of Mr. 

 Westwood " The insect has not the least appearance 

 of animation, and looks more like a small portion of 

 slime." 



The change of the Tenthredo usually takes place in a 

 silk-lined earthen cell or cocoon in the ground ; some, 

 however, burrow into the pith of the stem of plants, 

 while others construct a hard cocoon upon the twigs of 

 trees. A large oblong or long ovoid cocoon of this 

 kind is made by Trichiosoma lucorum, and is not un- 

 common on the thorn. When enclosed in the cocoon, 



