ol2 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



The principle worm that infests our trees is that which ia so 

 generally known as the •' measure worm." It is indeed one of 

 the geometra or span-worms, deriving its name from its method 

 of locomotion, not crawling like a caterpillar, but measuring its 

 length with each progressive movement. There are many vari- 

 eties of this genus, and among them, that most familiarly known 

 in New England, is the so-called " canker worm." This species 

 is somewhat smaller than the worm of New York, and I think, is 

 a longer lived animal, its span of life being protracted into the 

 month of August, whereas the measure worm of New York is not 

 to be seen after 1st of July, and generally disappears about the 

 20th of June. These worms disappear by "spinning yarn" from 

 the trees to the ground, in which they enter, there undergoing 

 the chrysalis transformation, to reappear after their change into 

 the butterfly or miller. 



The time occupied by the " canker worm" has long been noted, 

 and successful efforts have from this knowledge been adopted to 

 destroy them when in this form. The process ia as follows: 

 immediately upon their descent they change into the chrysalis, 

 which lies dormant for a longer or a shorter period, as affected 

 by the character of the season. But in the warm, thawy days of 

 early winter or in similar days of early spring, the newly formed 

 insects emerge from tlie ground, the female as a dark, wingless 

 grub. She, laboriously, starts upon her pilgrimage to the sum- 

 mit of the tree, slowly crawling up the trunk, and is met in her 

 path by the flying male. His duty of fecundation being finished, 

 he speedily closes his short life, while she continues her path till 

 she attains the ends of the branches from whence the young 

 shoots will proceed, and there she deposits in regular rows, some 

 fifty or more eggs, gluing them so fast to the limb that they can 

 with difficulty be removed. She finishes her task by covering 

 them over with a thick, gummy, dark colored crust, impervious 

 to water. Then she too closes her ephemeral existence. When 

 the warm spring sun has shed its revivifying rays over the earth 

 and the trees begin to put on their leafy mantle, the eggs thus 

 protected from the vicissitudes of the weather, which have been 

 carefully concealed by their dark covering from the searching 

 eyes of red-capped woodpeckers, the whistling bluejays, the 

 sonorous chicka-dee-dee, and other winter birds, begin to be 

 warmed into new life, and from them appear new worms in sea- 



