G 



ARSENATE OF LEAD AGAINST TOBACCO HORN WORMS. 



cation ; in addition, there were a large number of eggs on the plants, 

 and many of the young worms hatching from these eggs were not 

 killed until they wandered from the place of hatching. The same 

 is true of experiment No. 5, the If-pound dosage of Paris green. It 

 will be seen, however, that experiment No. 4, the arsenate-of-lead 

 application, was more effective than the Paris-green application, for 

 on the day of application there were at least 140 worms in experi- 

 ment No. 4, the arsenate-of-lead application, and only 114 worms in 

 experiment No. 5, the Paris-green application, while on the fourth 

 day after the applications there were only 31 live worms in experi- 

 ment No. 4, but 52 in experiment No. 5. 



The poisons were applied in the following series of tests in the 

 morning from 6.30 to 9 o'clock. The arsenate of lead was mixed with 

 an equal weight of dry wood ashes. All applications were made with 

 fan dust guns. The mixture of ashes and lead arsenate made a very 

 good dust and compared favorably in evenness with the application 

 of Paris green. Rain began to fall at 11.30 a. m. and continued in- 

 termittently until 2 p. m. Part of the rain was dashing. About one- 

 third of an inch fell. The first examination of the plats was made 

 after 3 p. m. of the same day. The tobacco on these plats was nearly 

 full grown and lapped in the rows considerably. 



Table II. — A comparison of the insecticidal effects against hormvorms of 

 arsenate of lead and Paris green in rainy weather. 



The three experiments recorded in Table II are very interesting. 

 They show, first, that arsenate of lead was far more effective during 

 rainy weather than was Paris green (see number of live worms on 

 the fourth day), even though a very heavy dosage of Paris green 

 was used ; second, that to be very effective during rainy weather an 

 application of at least 5 pounds of arsenate of lead per acre is re- 



