lOS CANKEK-WORM. 



MODE OF MIGRATING. 



May 24:. — Most of the worms nearly full grown, but others only half 

 grown. Many worms are leaving the defoliated trees by hanging down 

 upon their threads and trusting to the wind to swing them on to the 

 neighboring trees. When the wind blows freshly, the worms are car- 

 ried off nearly horizontally to a distance of many feet. 1 saw some 

 to-day floating thirty feet from the tree. As the web by which they 

 are suspended is scarcely visible, the worms often have the appearance 

 of fl} ing in the air. At the same time I could find very few worms on. 

 the trunk, showing that their normal way of migrating is not by crawl- 

 ing down the tree but by floating ofl* on threads. 



DIURNAL IN THEIR HABITS. 



Whilst the parent moths are noctural or crepuscular, the larvae are 

 diurnal in their habits. They are seen feeding and migrating by day, 

 and, having put twenty or more of them in a breeding cage, and exam- 

 ined them for a succession of nights, I always found them stationary 

 ©u the leaves, and often standing ofi" in horizontal or grotesque atti- 

 tudes. 



PRACTICAL TREATMENT. 



I will now give a condensed statement of a series of experiments 

 which I instituted, with the view of accomplishing the end so long 

 sought for in combatting this insect, namely : the preventing the female 

 moths from ascending the tree. As these females are destitute of 

 wings, they cannot, like most other insects, fly upon the trees, but are 

 under the necessity of crawling up the trunk, in order to deposit their 

 eggs upon the branches above. To prevent her so doing has been the 

 study of gardeners, fruit growers and amateurs for the greater part of a 

 century, and yet no contrivance and no application, at once simple, 

 cheap and effective, has ever been suggested. In the struggle for ex- 

 istence between man and the Canker-worm, the latter has thus far come 

 off victorious. Many expedients have been resorted to. A leaden 

 trough fitted around the trunk, and filled with oil, has been found the 

 most effective, and might be used to preserve a few choice trees ; but 

 it requires considerable attention to keep it in order, and it is altogether 

 too expensive for general use. The most common and generally ap- 

 proved method has been the application of a band of cloth around the 

 tree, besmeared with some adhesive substance, which will entangle the 

 feet of the ascending moths and hold them captive. For this purpose 



