10 MASS. EXPERIMENT STATION BULLETIN 353 



b. With sticky bands, as described under cankerworms. These bands should 

 be applied just before the caterpillars hatch. Frequent attention during the 

 time the caterpillars are present is necessary to keep the bands in good condition 

 and to kill the caterpillars below the bands. Here again it must be mentioned 

 that the young gypsy moth caterpillars may be carried by the wind. When there 

 is danger that an infestation may be established on a hilltop or other exposed 

 situation from which young caterpillars might be blown easily to other areas, this 

 method of tree banding is employed to protect trees in such locations from mi- 

 grating larvae. Applying sticky bands to the trunks of coniferous trees around 

 the edge of a pure stand, may also prove a helpful practice. 



4. Selective thinning. Because of the food preferences of the caterpillars 

 severe defoliation may be prevented by the removal of those deciduous hard- 

 woods which are preferred by the caterpillars. The number to be removed, of 

 course, depends upon the abundance of the preferred species and the size of the 

 trees. Serious defoliation is not likely to occur in stands of mixed hardwoods 

 where the volume of preferred foliage is less than one half of the total in the stand 

 and is evenly distributed. Stands of coniferous evergreens require a smaller 

 proportion of preferred foliage for the same degree of protection, and it may be 

 necessary to cut a barrier zone about 100 feet wide around them, in which all 

 preferred trees are removed, in order to protect the conifers from migrating 

 caterpillars. In some cases where conditions are especially favorable for an 

 increase of the insect, the presence of even small amounts of preferred foliage may 

 be dangerous. 



This practice of removing the trees preferred by the caterpillars, when used in 

 conjunction, with the control measures previously mentioned, should prove 

 valuable to owners of some types of woodlands which are in great danger of being 

 destroyed by this insect. If it is not feasible to apply artificial measures of con- 

 trol, this practice of thinning alone might prove of considerable value. The 

 work, however, should be done only by or under the direction of a person who is 

 acquainted with the feeding habits of the insect and understands the principles 

 of silviculture. In regions where practically the only trees present are those 

 highly favored by the caterpillars, this method of combating the gypsy moth 

 would not be applicable. 



Natural control. Many species of insects, both native and introduced, which 

 parasitize or prey upon various stages of the gypsy moth have been studied 

 and liberated in large numbers. These have been successful in reducing severe 

 infestations. During bad outbreaks of the caterpillars a wilt disease often kills 

 large numbers. 



Behre, C. E., Cline, A. C, and Baker, W. L. Mass. Forest and Park Assoc. Bui. 157. 1<336. 



Britten, W. E. Conn. Agr. Exp. Sta. Bui. 375. 1935. 



Burgess, A. F. U. S. Dept. Agr. Farmers' Bui. 1623. 1930. 



Felt, E. P. N. Y. State Mus. Mem. 8(1):116-123. 1905. 



Fernald, C. H. Hatch Exp. Sta. Mass. .A.gr. Col. Bui. 19. 1892. 



Mosher, F. H. U. S. Dept. Agr. Bui. 250. 1915. 



