20 



be reached in one waj- or another without much difficulty. The egg 

 mass is compact, and, being attached to the somewhat flimsy cocoon 

 and not to the bark, it is easily removed either by hand or by scraping 

 it off. The egg masses which have been scraped off must not be 

 allowed tb remain at the surface of the ground, but should be collected 

 and burned. A scraper for the removal of egg masses which occur too 

 high to bci^reached by hand has been devised by Mr. Southwick, of 

 Central Park, New York City, and consists of a very small hoe blade 

 at the end of a long pole. Perfectly unskilled labor can be utilized in 

 this operation, but the workman should be impressed with the neces- 

 sity of absolute thoroughness; not an egg mass should be overlooked. 



Fig. 7.— Silver maple leaves eaten by larvae o£ white-marked tussock moth in successive stages of 

 growth, from a (newly hatched larvse) to/ (full-grown larvae)— reduced (original). 



In the work against the gypsy moth in Massachusetts it has been 

 found that the egg masses can not be removed to the best advantage 

 by means of scrapers. The eggs are attached, not to the cocoons, but 

 to the bark of the trees, and certain eggs may be left in the attempt 

 to remove the mass. An extensive series of experiments has therefore 

 been carried on with a view to securing a liquid which will penetrate 

 and destroy the egg masses. 



A satisfactory liquid for this purpose has been found in creosote oil, 

 to which turpentine is added to keep it liquid in cold weather, with tar 

 to blacken it so that treated egg masses can be recognized at a glance. 



