No. 4.] THE GYPSY MOTH. 391 



methods. Although in oi^en and cultivated lands the de- 

 struction of eggs is considered one of the most efficacious and 

 practical methods of dealing- with the moth, this is not the case 

 in badly infested woodlands, where, unless fire is also used, 

 all that can be done by egg-killing, even at a great expense, 

 is to partially check the evil. Yet in badly infested localities 

 all the eggs possible must be destroyed to prevent a great 

 increase and dissemination of the caterpillars, for their ex- 

 pansive energy increases in proportion to their numbers. 



There are two methods of coping with woodland colonies, 

 which, under certain conditions, have proved more effectual 

 than egg-killing. These are spraying with arsenate of lead, 

 previously mentioned, and banding the trees with burlap. 

 Neither of these methods alone, however, can be depended 

 upon to exterminate, but either will dispose of most of the 

 moths. To secure extermination either of these methods 

 must be supplemented by others, such as egg-killing, cutting, 

 burning, etc., as circumstances may require. 



It is well known that in 1891 spraying with Paris green 

 for the gy ps}' moth proved to be a partial failure, and very 

 little spraying was thereafter done until the discovery and 

 successful use of arsenate of lead. Spraying, however, has 

 its disadvantages, and cannot be used over a large extent of 

 territory with results proportionate to the expense required. 



There is only about one month of the year during which 

 the most effective spraying for the gypsy moth can be done. 

 This period is from about the 15th of May, when the larger 

 proportion of the caterpillars have hatched out and the foliage 

 has reached a certain size, to about the 15th of June, when 

 all the caterpillars have appeared, and most of them have 

 reached an age when they will cluster under the burlap. If 

 within this short spraying season there are two or three 

 weeks of rainy weather, very little effective spraying can 

 be done, as the poison will not stay on the leaves unless 

 they are dry when it is sprayed on. Therefore, although 

 spraying may be very effective in certain localities and in 

 certain seasons, it cannot always be depended upon. The 

 short season also makes necessary a great expenditure for 

 spraying apparatus, if the work is to be carried on over a 

 large area. Furthermore, spraying must be done by com- 



