No. 4.] THE GYPSY MOTH. 439 



week or two, however, the labor of over 300 men began to 

 tell, and the number of caterpillars decreased so rapidly 

 that comparatively few were left to pupate. The killing of 

 the pupa? and moths was continued, until at the end of the 

 season the egg-clusters were rare, as compared with those 

 found in the same localities in the winter of 1897-98. 



Oil Burning. 



There were some infested localities overgrown with under- 

 brush (which could not be sprayed or otherwise treated early 

 in the season), where the caterpillars later appeared in 

 swarms. In some of these places the standing brush, on 

 the appearance of the caterpillars, was burned by the use of 

 the cyclone burner; in other places the undergrowth was 

 cut down and fire was run over the ground. Where either 

 of these methods was pursued, most of the caterpillars 

 were immediately destroyed by the fire, and the few that 

 escaped were driven to the burlaps on the trees and killed 

 there. Most of this burning was done in Maiden and Med- 

 ford. In other infested localities, where the undergrowth 

 could not be cut in season, the trees were burlapped and 

 most of the caterpillars upon them were taken under the 

 burlaps. Many of the survivors, however, retired to pupate 

 in the undergrowth, dead leaves or rubbish upon the ground. 

 On these pupae the cyclone burner was used with deadly 

 effect. In those large tracts of woodland in Maiden and 

 Medford which would have been burned over in the spring, 

 had the appropriation been granted in season, burning was 

 begun in July and continued through August and Septem- 

 ber, until the entire tracts were burned over. This burning, 

 while extremely effective upon the pupa? of the gypsy moth, 

 is also effective in destroying the eggs ; and, as it was impos- 

 sible to finish the work during the short season of pupation, 

 it was continued after the e^gs were laid. The intense 

 flame of the cyclone burner destroys dead leaves, sticks 

 and the like on the ground, and the eggs of the moth which 

 are deposited on or among these and other objects. The 

 great amount of this kind of burning to lie done made it 

 necessary to produce a machine which would burn over a 



