26 BULLETIN 78, U. S. DEPARTMENT OF AGRICULTURE. 



check plat. Three live larva; which had tunnelled in the stalks and were apparently 

 uninjured were found in plants in the poisoned plat. All treated plants had lived, 

 but were not as vigorous in appearance as those not treated. 



In experiment B, with arsenate of lead paste, the poison was used at the rate of 

 2 ounces to 2\ gallons of water. The tops only were dipped. One hundred plants 

 were treated and 100 left untreated. The plants were examined five days after trans- 

 planting. There had apparently been some injury from the poison, as the plants 

 were in best condition in the untreated plat, while those treated were somewhat 

 stunted or dwarfed. Eight injured plants were found in the poisoned plat. Five 

 plants were found injured in the untreated plat. 



PARIS GREEN. 



Paris green at the rate of one-fourth ounce to 3 gallons of water was used on 100 

 tobacco plants, and an adjoining row kept as a check. The entire plant was dipped 

 in each case, and the plants set out at once. The field was weedy. It had been 

 recently plowed and Crambus larvee were numerous. A light rain fell a few hours 

 after the plants were set. After eight days the plants were examined. Twenty-one 

 plants were injured by worms in the poisoned row and 26 in the unpoisoned row. 

 There had been some injury to the plants dipped in the poison solution, as the un- 

 poisoned plants had a more vigorous start. In some instances plants in the poisoned 

 row were only slightly eaten, thus indicating that the poison had acted as a repellent 

 or had poisoned the worm before the plant had been badly eaten. 



TOBACCO EXTRACT. 



One row of tobacco plants in a field was sprayed with a 500-to-l solution of tobacco 

 extract, 320 plants in all being treated. The solution was applied with a compressed- 

 air bucket sprayer. The substance did not prove effective in preventing injury. 

 On June 6, five days after the mixture was applied, the plants were examined. 

 Fourteen plants were found injured by worms in the sprayed row and 11 injured 

 plants were found in the unsprayed row adjoining. 



NICOTINE SULPHATE. 



A 1,000-to-l solution of nicotine sulphate was sprayed on 300 plants as in the fore- 

 going experiment, and an adjoining row used as a check. The plants were examined 

 four days after spraying. Eight plants had been attacked by worms in the sprayed 

 row and 13 plants in the check row. While the foregoing substances did not prove of 

 much value in' preventing injury from the worms, they seemed to repel flea-beetles, 

 as very few could be found on the treated plants whereas they were comparatively 

 abundant on the unsprayed plants. 



TOBACCO DUST. 



Tobacco dust was scattered about tobacco plants directly after planting. One row 

 containing 300 plants was used for the test and an adjoining row with the same number 

 as a check. Eighteen plants were found injured by worms in the treated row. Few 

 plants were found that were injured below the surface of the ground, the worm having 

 entered the plant at the "bud " or terminal leaf in most cases. Sixteen injured plants 

 were found in the row where the dust had not been applied. More of these plants 

 had been injured below the surface of tlie soil than where dust had been applied, this 

 indicating that the dust may possibly have some value as a repellent. 



KEROSENE. 



In the first experiment with kerosene the plants were dipped in a weak solution 

 of kerosene emulsion and were set out on June 15. Only 30 plants were used in the 

 test. None of these, when examined five days later, was found infested. There was 

 apparently no injury to the plants from the kerosene. Two infested plants were 



