INSECTS INJURIOUS TO TOBACCO 233 



By spraying three times, the worms may usually be entirely con- 



tro'led at much less expense than by hand-picking. The time of 



the spraying will depend upon the latitude and season, but it 



should be applied as soon as each brood of young caterpillars 



appears. Usually one spraying 



should be given about July 1st, 



a second early in August, and 



another in about two weeks to 



check the work of the second 



brood, which is the most inju- 



rious. One pound of Paris green FIG. 166. Southern tobacco-worm 



to 160 gallons of water is suf- ih cocoons of parasite. (After 



ficient, and it should never be 



used stronger than 1 pound to 125 gallons. Arsenate of lead may 



be used at the rate of 2 or 3 pounds to 50 gallons or dusted on as 



a powder. These treatments will also aid in controlling the bud 



worms. 



A method of killing the adult moths has been practiced by 

 many planters with satisfactory results. It consists of poisoning 

 the flowers of the Jamestown weed (Datura stramonium) with a 

 sweetened cobalt solution. The flowers are placed around the 

 fields in the evening, being set upright in holes in horizontal slats, 

 or supported by sticks. The cobalt solution is then introduced 

 into 'them by means of a quill, or dropper. It is composed of: 

 cobalt, 1 ounce; molasses, one-fourth pint; and water, 1 pint. In 

 their search for flowers the moths will be attracted by the odor of 

 molasses and the cobalt of the solution will poison them, and thus 

 prevent the female from laying some 200 eggs toward another 

 brood of worms. 



As the pupae hibernate in the soil it is evident that deep plowing 

 and thorough harrowing in late fall and winter of land which has 

 been in tobacco will result in destroying many of them. The 

 destruction of the stalks and cleaning up of refuse leaves after the 

 crop has been removed is also of importance, as the larvae may con- 

 tinue to feed in the field and become full grown and pupate 

 where by the destruction of their food this might be prevented. 



