334 INSECTS INJURIOUS TO VEGETATION. 



each female. The eggs are glued to each other, and to the bark, 

 by a grayish varnish, which is impervious to water ; and the clus- 

 ters are thus securely fastened in the forks of the small branches, 

 or close to the young twigs and buds. Immediately after the 

 insects have thus provided for a succession of their kind, they 

 begin to languish, and soon die. The eggs are usually hatched 

 between the first and the middle of May, or about the time that 

 the red currant is in blossom, and the young leaves of the apple- 

 tree begin to start from the bud and grow. The little canker- 

 worms, upon making their escape from the eggs, gather upon the 

 tender, leaves, and, on the occurrence of cold and wet weather, 

 creep for shelter into the bosom of the bud, or into the flowers, 

 when the latter appear. As this treatise may fall into the hands 

 of persons who are not acquainted with the habits and devasta- 

 tions of our canker-worms, it should be stated that, where these 

 insects prevail, they are most abundant on apple and elm trees ^ 

 but that cherry, plum, and lime trees, and some other cultivated 

 and native trees, as well as many shrubs, often suffer severely 

 from their voracity. The leaves first attacked will be found 

 pierced with small holes ; these become larger and more irregular 

 when the canker-worms increase in size ; and, at last, the latter 

 eat nearly all the pulpy parts of the leaves, leaving little more 

 than the midrib and veins. A very great difference of color is 

 observable among canker-worms of different ages, and even 

 among those of the same age and size. It is possible that some 

 of these variations may arise from a difference of species ; but it 

 is also true that the same species varies much in color. When 

 very young, they have two minute warts on the top of the last 

 ring ; and they are then generally of a blackish or dusky brown 

 color, with a yellowish stripe on each side of the body ;' there are 

 two whitish bands across the head ; and the belly is also whitish. 

 When fully grown, these individuals become ash-colored on the 

 back, and black on the sides, below which the pale yellowish line 

 remains. Some are found of a dull greenish yellow and others 

 of a clay color, with slender interrupted blackish lines on the 

 sides, and small spots of the same color on the back. Some are 

 green, with two white stripes on the back. The head and the 

 feet partake of the general color of the body ; the belly is paler. 



