174 A. M. FIELDE. 



Group d. Fifteen per cent, revived after seventy-two hours' 

 submergence, the first sign of revival appearing six hours after 

 removal from the water. These survivors lived several days, 

 but never resumed their normal activities. 



Group e. None survived eighty-eight hours' submergence. 

 Camponotus pennsylvanicus : Group f. Thirty-three per cent, 

 revived after forty-eight hours' submergence, and fully recovered. 

 The first sign of revival was given twenty hours after removal 

 from the water, and recovery occupied many ensuing days. The 

 ants were about fifteen millimeters in length. 



Group g. - - Fifty per cent, revived after seventy hours' sub- 

 mergence, the first signs of revival being given from twenty-one 

 to thirty hours after removal from the water. Full recovery did 

 not occur until after a lapse of many days : but twenty-five per 

 cent, were returned alive to a nest, where they met and were met 

 by their former comrades, with manifest pleasure. 



Group h. Only ants from fifteen to eighteen millimeters in 

 length were employed. After a submergence of ninety-five 

 hours, none revived. 



Such results show the futility of ploughing up ant-nests and 

 exposing the ants to spring rains as a means of exterminating 

 these pests on the farm. They indicate for this object the appli- 

 cation of heat to the nests, through any medium wet or dry, the 

 degree of heat being no less than 50 C. for any ants, and the 

 duration of the application being at least fifteen seconds for the 

 smallest ants and two minutes for large ones. Lured by greater 

 warmth, the ants assemble with their young at or near the surface of 

 the ground early in summer, and they would be surely destroyed 

 either by shoveling the nests, with their millions of developing 

 young, into a hot portable oven, or by saturating the nests in situ 

 with water duly heated. The ants that injure growing crops by 

 pasturing the aphides, their " milch cows," upon the roots and 

 stems, are small ones, and they would probably be killed by an 

 application of water hot enough to destroy the ants without 

 injury to the plant. 



The great tenacity of life in the ants and the distress evinced 

 by them during slow recovery or dissolution, should impel those 

 undertaking their extermination to do the work speedily and 

 effectually. 



