38 NEW YORK STATE MUSEUM 



eggs near the base of each leaf and when numerous may oviposit 

 on almost every leaf. One of the striking features of an infestation 

 is the general distribution of partly injured leaves throughout the 

 tree or even the entire orchard. 



The feeding on each leaf is, practically speaking, independent 

 of that upon other leaves. There is no inclosing and webbing them 

 together as with the fall web worm. The small caterpillars feed 

 almost entirely upon the upper surface, skeletonizing the leaves 

 more or less completely and working from the lower part of the 

 midrib upward and outward so that, unless the infestation is 

 unusually severe, areas on each side of the basal parts of the leaf 

 frequently remain untouched, as illustrated in figure 1, a type of 

 injury characteristic of moderately infested orchards. Those badly 

 infested may have practically every leaf on all the trees completely 

 skeletonized, as shown in figure 2. 



Food plants. This insect shows a marked preference for apple 

 though it has also been recorded by European writers as feeding 

 upon pear, hawthorn, mountain ash, birch and possibly willow. 



Natural enemies. Meyrick's statement to the effect that this 

 skeletonizer is local in England indicates moderately efficient natural 

 enemies, and this is borne out by its classification as a pest of minor 

 importance by Continental writers. Doctor Reh gives the following 

 list of parasites : Angitia glabricula Holmgr., M eso- 

 chorus pectoralis Rag., Microgaster species, Phygadeuon 

 and Thryptocera crassicornis Meign. It is possible 

 and certainly to be hoped that some of its native enemies have 

 become established with their host. If this is not the case the 

 chances favor certain of our native parasites becoming accustomed 

 to this new food supply and assisting materially in reducing its 

 abundance. One parasite, Dioctes obliteratus Cresson, 

 kindly determined by Mr Gahan through the courtesy of Dr L. O. 

 Howard, has already been reared from material received from 

 Westchester county. 



Control measures. There is no question but what thorough and 

 timely spraying with a poison, such as arsenate of lead, will destroy 

 the caterpillars and, owing to their feeding almost entirely upon 

 the upper surface of the leaves, a general application of these 

 measures in infested areas to all trees upon which the pest can 

 subsist would mean its early control and practical elimination so 

 far as material damage is concerned. Furthermore, the adoption 

 of such measures would be a most effective check upon a rapid 

 spread and consequent extensive injury. Residents of the infested 



