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 larve 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 
Jaid 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 
beneath 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-like, 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 all behave alike. 
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 larve 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 (Toririx), rep- 
resented by over two thousand species, are so named be- 
cause their very small larve mine in leaves, buds, young 
shoots, also in bark, root, and fruit. The leaf-rollers also 
