20 THE REPOKT OF THE No. 3^ 



Effect of Gas on Various Insects. 



The eifect of the gas was tried also on leaf-hoppers and aphis on rose, red 

 spider on salvia, tarnished plant bug and mites on aster and on cutworms. Temper- 

 ature 66.2° F. Relative humidity 89. Concentration 3 lbs. per 1,000 cubic feet. 



Result. Some leaf -hoppers died in 4 minutes, others in 14 minutes; red 

 spiders and aphis seemed to be killed in 8 minutes. The aphis do not remove 

 their beaks from the plant. On the insects being removed from the chamber at- 

 the end of 30 minutes, the capsids, cutworms and a few aphis that liad been 

 covered under a mass of leaves were still kicking feebly. After being exposed to 

 the air for one hour everything was seen to be dead. 



The action of choloropicrin on man is cumulative, and this would seem to be 

 the case with insects also. In most instances, insects that may be kicking feebly 

 when removed from the gas die after a while, even if placed in a current of fresli 

 air. 



Effect of rapid concentration. To determine if a sudden rush of gas would 

 prove more effective even in reduced quantity, choloropicrin at the rate of II/2 

 pounds per 1,000 cubic feet was heated in a retort over a spirit lamp and the ga& 

 introduced into the chamber through rubber tubing. Mealy bug on begonia were- 

 the insects and plants used. Temperature 68° F. Relative humidity 82. Thfr 

 gas was practically volatilised in 14 minutes. When heating ceased and the 

 plant was left in the chamber for two hours and then removed, on removal a few 

 bugs showed signs of life but these died in three or four hours. Unfortunately 

 tlie plant was withering at the time of removal. 



Experiments at night. Finally, gas was used on red spider and mealy bug at 

 night at a strength of 8.7 oz. per 1,000 cubic feet, temperature 59.0° F., relative 

 humidity 99. Plants used salvia and coleus. Exposure lasted 90 minutes and 

 by this time all red spider and mealy bug were dead; plants apparently normal. 

 Next morning both species of plants were withering. 



Inferences from fo^regoing experiments. It would seem that chloropicrin 

 cannot be used for greenhou.se fumigation as it has deadly effects on plants. 



Penetration in earth. To test the penetration of the gas in earth, a flower 

 pot about 7 inches deep, of ordinary greenhouse potting soil was used. Earth 

 worms and millipedes were placed at different depths. (1) On the surface, (2) 

 1^ inches down, (3) 5 inches down. Experiments done at night, concentration 

 at the rate of 8.7 oz. per 1,000 cubic feet. Time of exposure to gas 11 hours and' 

 30 minutes. Temperature 55.4° F., relative humidity 88. 



Result. Of those millipedes on the surface, some had crawled off the soil 

 and some into it. Those at 13^ inches depth had gone deeper. At the end of 

 the experiment all the millipedes and worms appeared dead, and while after 51/^ 

 hours the largest millipedes showed slight movement, the worms were all dried 

 up. Eight hours afterwards another large millipede was bending slightly, but 12* 

 hours after, all were dead without having moved from their original positions. 



Effect of Chloropicrin on House Furnishings. 



With a view to finding out if choloropicrin would have'any effect on furnish- 

 ings in houses, the following articles were exposed to its vapors for 12 hours: 

 bright steel, copper, brass, silver, oatmeal wall paper with gilt splashings, several 

 styles of lithographing in colors, cotton material, aluminum and varnished wood 

 {as of cabinets). Relative humidity 88. Temperature 55.6° F. 



