INTRODUCTION. XXXI 



Boll Worm, while Dr. Anderson and Judge Johnson represented the 

 Commission in their respective parts of the same State, making experi- 

 ments themselves and also assisting Professor Jones. Mr. Eoane was 

 located for some time at Selma, Ala., making extracts and decoctions 

 of various native plants in that region, while Judge Bailey represented 

 the Commission in the cane-brake region of the same State, and was 

 more particularly charged with what pertains to the food habits and 

 hibernation of the parent moth. In Georgia Professor Willet made a 

 series of experiments to test the value of fungus germs in the destruc- 

 tion of the worm. Professor Smith, of Tuscaloosa, Ala., was engaged 

 in the work on the cotton belt, represented in Chapter Yl. Prof. J. P. 

 Stelle, of Mobile, Ala., spent nearly five months in Texas, traveling 

 from place to place, under special instructions as to observations, while 

 Mr. Patton, in addition to assisting in the office work, spent part of 

 the summer at Selma, Ala. Here, also, Mr. Schwarz was stationed, as 

 we found it convenient to make this point a sort of field headquarters 

 for the work, especially the testing of remedies and remedial appliances. 

 Mr. Hubbard was stationed in Florida, principally at Centreville and 

 Crescent City. I>r. Barnard had his headquarters at Vidalia, La., in 

 the early part of the season, making notes in i)ortions of Louisiana and 

 Mississippi, but later in the season joined the force at Selma, where he 

 gave more particular attention to the machinery experimented with. 

 Whatever time could well be spared from the office w^ork of the Commis- 

 sion we devoted to field work, visiting during the months of July, 

 August, September, and October the different agents, and personally 

 aiding and suggesting in the carrying out of plans and instructions. 



These instructions were given in special corresi)ondence with the 

 agents, as also in Circular No. 7, and in the following supplementary 

 circular letter : 



SUPPLEMENTAEY INSTRUCTIONS TO .AGENTS. 



Office of the U. S. Entomological Commission, 

 No. 1700 13th Street, Washington, D. C, July 30, 1880. 



In addition to instructions already transmitted to you, I hereby call your atten- 

 tion to a few important points which should have especial attention. 



In the application of poisons already known to be effectual the great desideratum 

 is to ascertain the minimum quantity that can be used successfully. It is my inten- 

 tion to perfect appliances that will throw either an extremely fine mist or an almost 

 impalpable cloud of dust from near the ground up among the plants and on the under 

 side of the leaves. 



Test, therefore, thoroughly, by a series of experiments, whether : 



1. London purple, Paris green, or arsenic can be used without diluents by forcing 

 them dry in minimum quantity, onto the plants, and ascertaining how much ground 

 a pound of each may be made to cover. 



2. If they cannot be used without diluents, the minimum quantity of such diluents 

 necessary. 



3. How far, by fine spraying, and economy in preventing wastage on the ground, 

 the number of gallons of water to a pound of these materials may be reduced — the 



