Specific Pests 165 



spanworms, measuring-worms, and geometers, from the 

 manner in which the caterpillars move, drawing their hind 

 parts after them by curving the back, a motion due to their 

 having only two pairs of abdominal legs, are the larvae of 

 various species of moths, which are recognized by the fact 

 that the four wings are of the same color, ^ snow-white, 

 ash-gray, or yellow, — the caterpillars being mostly greenish 

 to brown, and striped or dotted. 



These worms are leaf-eaters, preying on maples, poplars, 

 willows, pines, etc., being especially destructive to elms. 

 The most injurious is the 



Spring Canker-worm. The eggs of this spanworm are 

 laid in patches on the trunk and limbs in early spring, the 

 caterpillars appearing at the end of April, and feeding 

 through May and June. During the last two weeks in 

 June they descend to the ground by silken threads, to pupate 

 beileath the soil surface. A few moths may come out in 

 the fall and lay their eggs, but the majority appear in spring, 

 The female is wingless and grub-hke, and ascends the tree 

 to deposit her eggs. 



The other canker-worms vary mainly in the time of their 

 stages of development, but in general ah behave aUke. 



Banding the trees in March prevents the ascent of the 

 females, thus forcing them to lay the egg masses below the 

 barrier, where the hatching larvae starve to death. Egg 

 masses can be mechanically destroyed by means of dendro- 

 lene, or otherwise. If these preventives have been neglected, 

 spray with arsenate, first when the leaves are half-formed, 

 and, if necessary, at intervals of two weeks. 



Leaf-miners {Tinea) and Leaf-rollers (Tortrix), rep- 

 resented by over two thousand species, are so named be- 

 cause their very small larvae mine in leaves, buds, young 

 shoots, also in bark, root, and fruit. The leaf-roHers also 



