290 PROTECTION AGAINST INSECTS. 



appear in July and August, pass two winters in their galleries, 

 and pupate in May of the third year, in a cocoon of wood-dust 

 constructed inside their borings, near to the ground ; excep- 

 tionally in the ground when the larva has bored low down 

 towards the roots of the plant. 



The images emerge in June, when the empty pupa cases 

 may be seen projecting from the stems. 



The generation lasts two years. The moth is widely distri- 

 buted and often common among poplars ; the injury caused 

 by the caterpillars often accompanies that of Saperda car- 

 charias, L. (page 280). 



c. Relations to the Forest. 



The larva bores cylindrical galleries in the wood of poplars, 

 especially of the black poplar and aspen. As a rule it prefers 

 trees less than 20 years old, but is sometimes found in older 

 trees. It generally bores low down in the tree, and its attack 

 can be recognised by the wood-dust which collects on the 

 ground or blocks up the holes by which the moth will emerge, 

 and through which the pupa can push itself by means of its 

 spines. The injured saplings are frequently broken by the 

 wind. The caterpillar is chiefly injurious in nurseries and 

 avenues. 



d. Protective Rules. 



Saplings may be smeared as for protection against the poplar 

 longicorn. The moths should be caught on the tree-trunks 

 and destroyed at the end of June. Saplings infested with 

 larvae should be cut down. 



FAMILY II. COSSIDAE. 

 Description of Family. 



Imagos of this family of wood-borers with setaceous or 

 bipectinate antennae; without ocelli; the mouth-parts rudi- 

 mentary. Body stout, and covered with close short hairs. 

 Flight nocturnal, the wings strong, and roof-shaped when at 

 rest. Generation extending over 2 or more years. Caterpillars 

 smooth or cylindrical, and with a few scattered hairs. Pupae 



