34 NEW YORK STATE MUSEUM 



since some of our most destructive introduced species are of relatively 

 slight importance in their native countries. The caterpillars feed 

 upon the upper surface of the leaves almost entirely and it is, 

 therefore, relatively easy to apply poison where it will do the most 

 good. This considerably simplifies the problem of control and 

 renders it fairly easy to keep this pest within bounds until its status 

 can be determined or natural enemies have an opportunity to assert 

 themselves and prevent widespread and material damage. The 

 insect is already sufficiently numerous near the center of the infested 

 area to defoliate entire orchards and conditions favor a continuation 

 of the spread with its accompanying serious injury unless there is 

 early, thorough and general spraying in the infested area next 

 summer. 



Recognition characters. This pest skeletonizes apple leaves in 

 much the same way as the well-known canker worms, except that 

 these latter more usually devour all the vital tissues of nearly every 

 leaf, whereas this newly introduced caterpillar generally confines 

 its attack to portions of many leaves (frequently practically all the 

 leaves on a tree may be eaten in this manner), feeding near the 

 center under a slight web and extending upward and outward to 

 include most of the tip of the leaf as illustrated in figure i . Areas 

 on each side of the basal part of the leaf are often untouched. 

 Frequently the margins to the width of one-half of an inch or so are 

 turned over and a badly eaten leaf may present the appearance 

 illustrated in figure 2. There is no webbing together and inclosing 

 leaves in masses so characteristic of the native fall web worm and 

 also seen to a less extent in the nests of the brown tail moth cater- 

 pillar. Both of these last-named species produce moderately firm 



to thick webs which inclose the 

 leaves, something never done by 

 this newly introduced insect. 

 Moreover, the caterpillar of the 

 apple and thorn skeletonizer is 

 active, yellowish, black-spotted, 



1 ■ practically naked and about half 



Fig. 3 Apple and thorn skeletonizer, an ^ j whereas both of 



an unusually well marked moth. The . 



coloration varies greatly. (X 4) (Au- the above-mentioned tent-mak- 

 thor's illustration) ing caterpillars are distinctly 



hairy, slower in movement and, 

 when full grown, an inch or more in length. 



Description. The moth (figure 3) is an obscure grayish brown o r 

 dark brown, sometimes purplish tinged, insect with a wing spread of 



