181 OHIO EXPERIMENT STATION: BULLETIN 194 



paper. Ses Plate 7, Fig-. 1. At the time of the treatment, the first 

 brood of larva was beginning to give evidence of its presence by its 

 work upon^the leaves. 



Both sprays killed the feeding larvae and the trees were prac- 

 tically free from the insect during the entire season, whereas, their 

 untreated neighbors were partly defoliated. The sticky materials 

 upon the bands was replenished once during the summer with a 

 coating of Thum's tree tanglefoot. 



The third measure looking toward control that was tried ex- 

 perimentally, was the application of strong kerosene emulsion at the 

 time the first brood of larvae was transforming to the pupal stage. 

 Horse chestnuts that had been defoliated by the first brood were 

 heavily sprayed with strong kerosene emulsion July 20. The trees 

 were located in front of 2236 84th St. SE. Directly adjoining these 

 trees were other horse chestnuts that were left unsprayed for con:- 

 parison. The comparison however was not a fair one as the un- 

 . treated trees had in no wise suffered as severely as had the others. 

 An idea of the appearance of the tree at that time of treatment may 

 be had from Plate 6, Fig. 1. 



August 30", the tree was again photographed as shown in Plate 

 6, Fig. 2. At the later date scarcely a single larva could be seen 

 upon the treated trees and a small crop of new foliage had growq 

 meantime; while enough larvae had escaped the parasites on the 

 untreated trees to do considerable harm. A comparison between 

 the treated and untreated trees may be drawn from Plate 7, Fig. 2. 

 It may also be seen where some larvae from the untreated tree had 

 gained access by means of the interlocking branches to the treated 

 tree, and had destroyed a portion of the second crop of foliage. 



As a general specific measure to be used in combatting thi^ 

 pest, the author believes there is nothing more effective and prac-. 

 ticalthancollectingor treating the egg masses during the wintei 

 months and keeping the trees banded with tanglefoot from the 

 middle of June until the first killing frost. This measure is es- 

 cially commendable for individual operations as the cost would not 

 be excessive to hire nimble workmen to climb the trees and destroy 

 the egg-masses. It would only remain to keep the bands in good 

 working order. If the work of destroying the cocoons is thoroughly 

 done and the trees so treated are not close enough to neighboring- 

 trees so that the young caterpillars are able to span the distance 

 ^yith their webs, there is no reason why careful banding alone should 

 not keep the trees free of this pest. 



If impossible to collect the egg masses, spraying with arsenicals 

 is next in order but it too should be supplemented with banding and 

 the mixture should be applied while the larvae are young. 



