REPORT OF THE ENTOMOLOGIST, 30,9 



concerted action cannot be obtained good results will follow individual 

 efforts. For, although the summer and autuuni broods of niotlis migrate 

 to great distances, there is reason to believe that the hibernating indi- 

 viduals and those of the early broods do not do so to any great extent. 

 As evidence of this we cite the fact that considerable time elapses be- 

 tween the appearance of the worms in those localities which we have 

 designated as centers of hibernation and in the more northern parts of 

 the cotton belt. 



Destruction of larvae by poisons. — In the present state of our 

 knowledge it seems that the most effectual means of destroying the cot- 

 ton-worm is by the use of i^oisons, either in the moist or dry condition. 

 In the former case, the poisonous substance is dissolved or suspended 

 in water ; in the latter, it is mixed with flour, gypsum, or other innocuous 

 powder, which serve to dilute it, and in some cases to aid it in adhering 

 to the plant. 



During the season of 1879 a careful and extended series of experi- 

 ments were conducted by Mr. William Trelease, under my direction, for 

 the purpose of ascertaining the best poison for use, taking into consid- 

 eration both its elGcacy as an insecticide and its effect on the plant. 

 Special attention was also given to ascertaining the most rapid and 

 economical method of appljring poisons. 



These experiments were performed under especially favorable condi- 

 tions. Mr. Trelease was located upon a plantation in the southern part 

 of Dallas County, Alabama, a locality in which cotton- worms are espe- 

 cially destructive ; he made arrangements by which he could call into 

 service all the help on the place if necessary. In this way he was able 

 to use the remedies on a large scale, and to carefully compare the results 

 obtained by different methods. A neighboring plantation upon which 

 no efforts were made to protect the cotton served also for comparison. 



As we shall have occasion to refer to these experiments we give here 

 a part of Mr. Trelease's report relating to them. 



The ground covered by my experiments with poisons may be seen from the follow- 

 ing tables : 



I. — To TEST THE EFFICACY OF THE SUBSTANCES. 



(a) London pui-ple, suspended in water. 



(b) Gray arsenic, suspended in water. 



(c) Paris green, suspended in water. 



A Tyg+ J {cl) Texas worm-destroyer, dissolved in water. 



■ j (e) Gray arsenic, in Fowler's solution. 

 (/) Oil of turpentine, in water. 

 I (g) Kerosene, in water, 

 l^ (hS CarTiolic acid, in water. 

 ( (a) London purple, in Royall'a mixture.* 

 B. — Dry. < (b) Gray arsenic, in Royall'a mixture. 

 I (c) Paris green, in Royall's mixture. 



II. — To TEST THE ADHESION OF THE SUBSTANCRS, 



A -yy i 5 (^) Poisons suspended in water without flour-paste. 



\ {b) Poisons suspended in water with flour-paste. 



j (a) Poisons mixed with flour. 

 (b) Poisons mixed with flour and gyj^sum. 

 B. — Dry. < (c) Poisons mixed with flour and rosin. 



1 (ri) Poisons mixed with flour and dextrine. 



l^ (e) Poisons mixed with flour, rosin, and dextrine, t 



* Royali's patent : Flour, one barrel, 196 pounds; Paris green, 9 pounds; dextrine, 

 10 pounds ; rosin, 12 pounds. 



The ingredients being in a fine powder, are sifted to remove lumps, after which tbey 

 are thoroughly mixed. Other poisons may be substituted for Paris green. 



ilbid. 



