BUENING THE EGGS. 119 



then in use. Egg-killing was begun by the commissioners, 

 who, fearing that spraying might not prove effective, deter- 

 mined to leave no stone unturned, but to give all promising 

 methods a thorough trial. 



Burning the Eggs. 

 Professor Fernald had recommended in 1889 that the eggs 

 of the moth be scraped from the trees and burned. This 

 was the most effectual method of egg-killing pursued by the 

 first commission. During the spring of 1891 it was used 

 by the second commission and later by the employees of the 

 State Board of Agriculture. The eggs were scraped off or 

 cut away from the objects upon which they rested, placed in 

 tin cans and burned in stoves or brush fires. A fierce heat 

 is required to ensure their destruction. When exposed to 

 such heat they finally burst with a snapping like a bunch of 

 miniature fire-crackers or the cracking of corn in a popper. 

 Whenever the eggs were very numerous in undergrowth or 

 waste land, fire was run through the dead leaves and debris 

 as an experiment; but this method seemed to have little 

 efiect, as the heat was not sufficiently intense. The hairy 

 covering of the egg-clusters seems to possess remarkable 

 non-conductive properties, rendering the eggs almost imper- 

 vious for a time to sudden intense heat. Even with the 

 hottest fire that can be applied to the egg-clusters, some 

 minutes are required to destroy them utterly. A running 

 brush fire merely scorched the outside of the cluster, killing 

 perhaps a few of the eggs in the external layer, but leaving 

 the majority uninjured. Experiments were next made with 

 crude petroleum, by spraying it over the ground and vegeta- 

 tion by means of watering pots and then igniting it. The 

 fire thus made was fierce enough to destroy the small under- 

 growth and the upper layer of leaves, together with most 

 of the eggs, but such egg-clusters as remained under roots 

 or rocks were not injured. Considerable oil was wasted by 

 soaking into the ground, and the remainder did not give 

 the degree of heat which is obtained l)y atomizing. Experi- 

 ments were then made with a view of perfecting a burning 

 machine which would incinerate all undergrowth in a given 

 tract. The first experiments were not entirely successful, 



