Suppression of the Gipsy and Brown-tail Moths. 7 



in this country, and is a powerful agent in curtailing the 

 increase of the species. The character of the food plants 

 is also of great importance. The tree growth of the infested 

 region has been classified according to its adaptability as 

 food for the gipsy moth. It has been found that practically 

 all coniferous growth, if grown in solid stands, fails to sup- 

 port this insect; that ash is not subject to attack, and that 

 maple and hickory are seldom injured to any great extent. 



An effort is being made to encourage the growth in wood- 

 lands of the tree species just mentioned, and to discourage 

 the growth and planting of oak, willow, and poplar, which 

 are favored foods. Unfortunately the greater part of the 

 infested area abounds in oak growth which, for the most 

 part, is of poor quality and has a very low merchantable 

 value. This fact discourages greatly the elimination of fa- 

 vored food plants in the infested area. Nevertheless some 

 progress has been made in eliminating favored food plants 

 in the heavily infested areas. Thinning work is being car- 

 ried on by the Bureau of Entomology in the isolated 

 colonies near the borders of infestation also, but in addi- 

 tion it has been necessary to treat the egg clusters found in 

 these areas and to reduce the caterpillars by the application of 

 sticky bands to the trees and by thorough spraying in order 

 promptly to prevent further spread. The importation and 

 colonization of natural enemies has served to reduce the in- 

 festation in the many localities in the worst infested sections. 

 These factors are bringing about a gradual reduction in the 

 main supply of the insect which, in case they were not em- 

 ployed, would serve as a stock for further distribution of the 

 pest. Every effort is being made to prevent long-distance 

 spread of both insects by carriage on products shipped to 

 points outside the infested area. The territory infested is 

 under quarantine by the Federal Horticultural Board and 

 all products likely to carry the insect out of the infested 

 area are inspected before they are allowed to be moved. 

 The border territory is thoroughly inspected and the gross 

 infestation in this region is being gradually reduced. It is 

 inevitable that new colonies will be found from time to time 

 outside the region now known to be infested, but substantial 

 progress is being made in preventing any widespread dis- 

 persion of the insect. 



