August, '08] JOURNAL OP ECONOMIC ENTOMOLOGY 265 



was added from time to time to preserve the requisite amount of 

 moisture within the cage, resulted in small cavities being formed 

 outside the nest. From time to time a mite would find its way into 

 one of these cavities and would remain there for a longer or shorter 

 time. Such mites were constantly watched over by a detail of from 

 two to six workers from the colony and while the workers never fed 

 or in any other manner cared for the mites, so far as could be deter- 

 mined, they were nevertheless unremitting in their self-imposed 

 guardianship both day and night. 



That the mites were in no way dependent upon the ants for food or 

 for care was determined by placing several hundred of the former in 

 a plain glass bottle with a small supply of worker and larva "cad- 

 avers" and other refuse matter taken from the cemeterial chamber of 

 a large artificial formicarj'. Water was added from time to time to 

 keep the mass sufficiently moist and the bottle isolated by water to 

 prevent any living ants from obtaining access to it. On this dead and 

 decaying matter the mites lived and thrived for over sixty days, when 

 other duties caused us to neglect the daily application of moisture 

 and the death of the mites resulted. 



We therefore feel safe in venturing the opinion that these two 

 mites are scavengers, pure and simple, in the colonies of the Argentine 

 ant and as such they are tolerated by the latter, although their pres- 

 ence is not necessary to the welfare of the community and no effort 

 is made by the ants to secure or retain their services. 



Careful search in the colonies of other species of Formicina has 

 thus far failed to reveal the presence of either of these two species 

 of Uropoda. 



Baton Rouge, La., June 22, 1908. 



THE FUNDAMENTAL PRINCIPLES OF SPRAYING 



By H. T. Ferxald, Amherst, Muss. 



The use of arsenical poisons in the control of insect pests has 

 now continued for nearly half a century. During that period, start- 

 ing with but a few pounds a year, the demand has increased until 

 many tons of these materials are now annually consumed and their 

 use is one of the fundamental principles of economic entomology. 

 Yet, a careful examination of our actual knowledge of arsenicals in 

 their relation to insect and plant life gives surprising results, showing 

 how little is really known and how much is merely empirical, and in- 



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