246 THE GYPSY MOTH. 



Many Food Plants. — AVhere the moth is abundant, it is 

 found on nearly all plants of economic value. In inspecting 

 a region in search of the moth it is necessary to examine all 

 species of trees. It is therefore much more difficult and 

 expensive to locate all the colonies than it would be were 

 the insects confined to a few food plants. 



Other Obstacles. — The infested region being densely pop- 

 ulated, the danger of local distribution and reinfestation by 

 man and animals constantly passing and repassing infested 

 centres is much greater than it would be were the district 

 thinly populated. 



Ko one method can be depended upon for exterminating 

 the moth. Xature often defeats an attempt to exterminate 

 by a single process at a particular season of the year. 

 The most approved methods applied singly fi-equently fail, 

 Exterminative work must proceed da}"" after day throughout 

 the year, to insure success. Though every effort was made 

 in 1891 to exterminate the moth from the region most in- 

 fested, the inspection of 1892 gave abundant evidence of the 

 impossibility of extermination in one year's time. In 1891 

 the destruction of the eggs was depended upon for extermi- 

 nation. Yet caterpillars were found in 1892, even in those 

 parts of the infested territory where the work had been most 

 carefully done, and where the greater part of the eggs had 

 been destroyed. Manv of these came from esfffs which had 

 been scattered on the ground in the previous fall and winter 

 before the work of destroying the clusters was begun. Eggs 

 are sometimes thus scattered by the wind and rain, by 

 people picking fruit or pruning or cutting trees, by birds 

 and animals, or b}^ various other causes. The female moth 

 occasionally drops a few eggs upon the ground or in crevices 

 of the bark, where they will escape the most thorough 

 search. Spraying, as ordinarily done, will destroy only a 

 small portion of the caterjiillars. Bands of insect lime and 

 other tree protectors merely prevent most of the caterpillars 

 from ascending trees which have been first cleared of eggs. 

 If thus kept out of trees, they will betake themselves to 

 other plants. AYhile the burlap bands afford a means of 

 disposing of most of the caterpillars, there can be no cer- 

 tainty of taking them all by this method. 



