April, '08] JOURNAL OP ECONOMIC ENTOMOLOGY 115 



bolls opened and furnished fair lint, with improperly filled seed, while 

 the smaller bolls either dropped off or decayed after opening slightly. 



Copper sulphate used at the rate of 5 lbs. to 50 gallons of water 

 scorched the foliage slightly and induced gradual shedding of leaves. 

 This shedding, however, was accompanied by a constantly increasing 

 rejuvenescence of the plants. 



A 10% solution of iron sulphate killed leaves, squares and the 

 smaller bolls. 



A 5% solution of iron sulphate was next tried. The action of 

 this solution was more gradual than that of the 10%. In 24 hours 

 after application some leaves were burned. Three days after the 

 application blossoms and forms were dead and on the fourth day 

 the shedding of leaves, squares and forms was well under way. By 

 the fifth day there was practically nothing upon the plants that 

 could serve as food for the weevils. This slow killing of the foliage 

 also gave the large bolls, not open at time of spraying, an oppor- 

 tunity to mature, for on the fifth day also the first of these opened. 

 For several days afterwards these bolls opened rapidly and from 

 those that were three-fourths grown or over at the time of spraying, 

 fair lint was secured. Lint in bolls which were open at time of 

 spraying was slightly discolored. Later a very few green shoots were 

 put out by these plants. We have given the results of this experi- 

 ment thus in detail for iron sulphate meets the requirements better 

 than any other substance tried and it is also the cheapest. 



The iron sulphate and salt solutions having separately proved the 

 most promising, they were tried in combination. A solution contain- 

 ing 5% of each did not show any advantage over the 5% solution of 

 iron sulphate used alone, and the plants sprayed with the former 

 took on new growth to a marked extent. 



Combinations of iron sulphate and white arsenic were tried, but 

 gave no indication of being better than iron sulphate alone. 



A 1% solution of iron sulphate was not found to be strong enough. 

 A 3% solution of the same material was practically as effective as the 

 5% solution, except that the plant recovered to a certain extent and 

 in a couple of weeks put out more new foliage than was desirable. 



Taking a comprehensive view of these experiments, we see that ar- 

 senic solutions proved effective in killing the plants, but are too ex- 

 pensive, while iron sulphate solutions meet the requirement of killing 

 the plants slowly, while at the same time permitting the larger bolls 

 to mature and open. The latter — nearly grown bolls — it may be re- 

 marked, are the ones which are 'lost when the plants are uprooted 

 and burned; smaller bolls would not figure in the production, as in 



