144 ASSOCIATION OF ECONOMIC ENTOMOLOGISTS. 



tinued for a long time, will destroy insects in grain and seeds, and 

 has considerable penetrating power. 



Note. — In the case of all these tests 10 to 15 packages of various seeds were 

 included to be tested for effect on germination. The reports on these tests are 

 appended to this article. 



Experiment No. 8. 



An. experiment to determine the effect of the gas on miscellaneous 

 insects, household pests, grain pests, and the powder-post beetle 

 (Lyctus) in manufactured wood products — furnished by Doctor Hop- 

 kins. The insects submitted to the test (except those in the wood 

 material) were in cloth-covered glass jars or in glass cylinders cloth- 

 covered at either end, containing grain. These were placed in the 

 house, opposite the windows, so that the effect of the gas and the exact 

 time of the death of the insects could be noted. The wood material 

 was placed in the building, but of course the action of the gas on this 

 material could not be followed. The experiment began at 2.15 p. m. 

 and continued until 10 o'clock the next morning, a total of nearly 20 

 hours. In charging the building, necessarily the beginning was with 

 a low percentage of gas, which worked up to the full amount of 6 per 

 cent in 30 minutes. After 15 minutes' pumping a test of the gas in 

 the house indicated 2 per cent and after 25 minutes 5 per cent. Five 

 minutes under pressure brought the gas up to 6 per cent in the build- 

 ing, 7 per cent at the machine, and further charging was discontinued. 

 After 1 hour the gas in the building still indicated 6 per cent ; after 2 

 hours, 5^ per cent ; after 4 hours, something more than 3 per cent, and 

 at the end of the experiment, about 1 per cent. 



The immediate effect on the insects noted below was chiefly with 

 a very low percentage of gas; in other words, all effect noted prior to 

 the expiration of 15 minutes was with gas of less than 2 per cent 

 strength, and at 7 .minutes the gas was doubtless less than 1 per cent 

 in the building. 



SUBJECTS OF EXPERIMENT. 



(1) Honey bees (Apis mellifera L.) : Semiunconscious and fallen 

 to bottom of jar in 7 minutes; all motion ceased at 10 minutes. 



(2) German roaches (Blattella germanica L.) : Down and appar- 

 ently dead in 7 minutes. 



(3) Bedbugs (Cimex lectularius L.) : Down and motionless in 10 

 to 15 minutes. 



(4) Monilema sp : Sluggish in 15 minutes; quiet in 20 minutes. 



(5) Miscellaneous insects, several orders, including Orthoptera, 

 Hymenoptera, Hemiptera, Diptera, and Arachnida (complete list be- 



