INSECT PESTS OF OHIO SHADE AND FOREST TREES 209 



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mer, whether it be second or third as the case may be, constitute 

 the overwintering stage. 



Nature of injury. The newly-hatched caterpillars begin feed- 

 ing upon the tender epidermis of the leaf of the host. As they 

 develop in size and correspondingly in appetite and gastric ability, 

 they devour the entire leaf structure with the exception of the 

 midribs. When they are sufficiently plentiful the host may be 

 defoliated, as shown in the accompanying illustrations, Plate XVIII, 

 Figs. 4 and 5. Frequently the first brood of caterpillars devours 

 the first crop of leaves, and the second brood in turn consumes the 

 second output of leaves. Such a procedure seriously checks the 

 development of a tree and lowers its vitality, thus rendering it sus- 

 ceptible to furttuer harm by other agencies. Because of this fact 

 a tree sometimes succumbs following repeated attacks by this in- 

 sect, but as a rule the attacks do not prove fatal. Dr. E. P. Felt (3) 

 cites an instance where the injury constituted the girdling of elm 

 twigs at the beginning of the season's growth. This caused the 

 twigs to die, break off and fall to the ground. Several instances 

 are -on record where the caterpillars have proved capable of severe 

 injury to fruits. One of the most recent and most destructive 

 occurred in western New York (4) where in some instances 85 per- 

 cent of the fruit was mutilated by the feeding insects. Within 

 recent years, and particularly the last two, young apple trees in 

 some sections of Ohio have been injured perceptibly by the cater- 

 pillars of this species. 



From the city standpoint the chief harm inflicted constitutes 

 the partial or complete defoliation of the trees and the consequent 

 detraction from their beauty and utility. Of less moment but not a 

 negligible item, is the unsightliness of the egg masses and old 

 cocoons as they adhere during the winter to tree trunks, sides of 

 buildings, fences, etc. Unless removed by some mechanical method, 

 these objects remain in place during the entire winter and give the 

 property a neglected appearance. 



Food plants. Doctor Felt (5) reports the following list of food 

 plants: "Linden*, horse-chestnut*, buckeye*, maples* (especially 

 the soft and Norway) , box elder, honey locust, apricot, garden plum, 

 wild plum, garden cherry, chokecherry, rose, pear, apple, quince, 

 ash, elm* (several species), sycamore or buttonwood*, butternut, 

 black walnut, hickory, oak, birch, alder, willow, poplar, spruce, fir, 

 larch and cypress." 



The species has been noted as feeding in Ohio on most of the 

 trees of the foregoing list and in addition has been noted on witch 



