February, '13] BURGESS & ROGERS: GIPSY MOTH FOOD PLANTS 77 



■experiment. The oak and all other trees, except chestnut, and a 

 few conifers, were removed and the brush and slash burned. This 

 left a stand of chestnut trees averaging 35 to 45 feet in height, all of 

 which were badly infested. No detailed observations were made 

 during the early summer, but occasional visits by Mr. Rogers during 

 the season failed to indicate any defoliation of the chestnut trees. 

 Since that time the brush and sprouts have been, allowed to grow 

 and while the trees have not been injured by caterpillar feeding, the 

 oak sprouts have furnished enough food so that the infestation is 

 slightly greater than it was in the fall of 1911. 



During the same winter another block of woodland in Methuen, 

 Mass., covering about twenty-five acres, was thinned as an experi- 

 ment. One section of this woodlot covering perhaps four acres con- 

 sisted mainly of white pine with scattering oak trees and undergrowth ; 

 the balance consisting of red and white oak, gray and yellow birch and 

 red maple. The latter species was particularly common on the low 

 ground and in some parts of this area several small groups of hemlock 

 trees were growing. The section where pine predominated was thinned 

 to solid white pine growth, while in the oak and maple area all the oaks 

 were cut except a few specimen trees. On the lower land all oaks 

 and birches were removed leaving red maple, and in a few places 

 hemlocks and an occasional pine. A part of the trees growing on the 

 high ground was badly infested and the infestation decreased slightly 

 on the lower ground where more maples were growing. In the spring 

 of 1911 the trees on the higher area were banded with tanglefoot, 

 where this lot joined a badly infested woodlot, but no other treatment 

 was applied and no serious injury resulted except to some of the oaks. 

 The infestation over the entire area decreased remarkably as a result 

 of the thinning. This fall, 1912, practically all of the trees, except 

 the oaks, are in good condition. A slight infestation can be found 

 throughout the entire area but it is apparent that no injury to the 

 trees is likely to result from it. This woodlot has been used as a 

 pasture for cattle so that very little sprout growth exists. 



In order to follow up the results of making experimental thinnings 

 and to attempt to secure more information on this important phase 

 of the gipsy moth work, as well as to obtain field data which could 

 be used in, connection with an extensive series of laboratory feeding 

 experiments, which were made during the summer of 1912, a number 

 of areas were thinned during the winter of 1911-12 under the direc- 

 tion of the writers. 



In Hudson, Mass., an area of chestnut, maple, red and white oak, 

 gray birch and ash, with various kinds of undergrowth which was 

 slightly infested, was thinned to a chestnut stand and all specimens 



