3o8 



A A' ECONOMIC ENTOMOLOGY. 



grown, descend to the ground to pupate ; when the females 

 emerge they crawl up the trunks of the trees, where they are 

 fertilized by the males, and then continue their journey to the 

 leaves, upon which they lay their eggs. This habit gives us 

 control of the insects, for if we simply band the tree in such away 

 as to prevent either the female or the young caterpillars from as- 

 cending to the branches, it will be protected completely. Unless 

 the female can get upon the leaves, the eggs are laid upon the 



trunk below any obstruction that it cannot pass. The young 

 larvae will attempt to get to the leaves, and will, if they find an 

 impassable barrier, starve to death. The best materials, all 

 things considered, are " raupenleim, " or " dendrolene," prefer- 

 ably the latter, as it remains viscid for the full period during 

 which the insects hatch, and forms a perfect barrier beneath or 

 through which no creature can crawl and live. A band six 

 inches in width and a quarter of an inch or more in thickness 

 over thick wTapping-paper will prove a perfect protection. Fluffy 

 wool or cotton may also be employed, and the former is the most 

 lasting, but less certain than the ' ' dendrolene. ' ' 



A near relative of these canker-worms is the ' ' lime-tree moth, ' ' 

 Hybernia tiliaria, which also attacks a variety of trees, and has 

 at times been decidedly troublesome. The application of the 

 arsenites will prove a complete protection in this case ; indeed, we 

 may say of all the caterpillars belonging to this family, including 

 the " canker-worms," that they can be controlled by the thor- 

 ough application of stomach poisons to the plants upon which 

 they feed. 



Fig. 351. 



Canker-worm, larva of Paleacrita vernata. — 

 a, b, egg, enlarged ; e, patch of eggs ; c, d, body 

 segments of f, larva; g, pupa of female. 



a, larva of Anisoptejyx pome- 

 taria; b, an egg, much enlarged ; 

 c, d, body segments of larva. 



