148 ASSOCIATION OF ECONOMIC ENTOMOLOGISTS. 



The bags of infested grain used in this test were kept free from 

 a chance of reinfestation, and two months later were carefully exam- 

 ined with the following results: The infested grain buried in the 

 middle of the zinc-lined box, namely, at a depth of about 9 inches, 

 contained only dead insects, the penetration and destruction of insect 

 life being perfect in this case. The insects represented were prin- 

 cipally Calandra oryza and Ateleopterus tarsalis Ashm., a parasite of 

 Silvanu.s surinatnensis. The sack at the bottom of this chest, namely, 

 at a depth of 18 inches, exhibited the same results, and contained, in 

 addition to the above, Meraporus calandrcv How., a parasite of C. 

 oryza^ and one beetle of Tenehroides Tnauritanicns L. 



The sacks of infested grain placed at the bottom of the earthenware 

 jars, namely, at a depth of 11 inches, exhibited, after two months' 

 standing, living insects. (All were dead, apparently, at the conclu- 

 sion of the experiment.) The insects represented are C aland rn oryza 

 and its parasite, M. calandra', and of these only about 50 per cent had 

 been killed. There was also found one living larva of T. maaritani- 

 cus. The test in this latter case was a very severe one, for the reason 

 that the jars were narrow and the surface exposed at the top for direct 

 penetration was only 5 or 6 inches in diameter. In the case of the 

 zinc-lined chest there was a superficial area for direct penetration of 

 4 or 5 square feet. 



Experiment No. 12. 



To test the etfect of the gas on wall paper and lacquered brass and 

 nickel. 



The material was subjected to 5 per cent of the gas for 3| hours, 

 with occasional pressure of a few minutes at a time to test the strength 

 of the gas in the building. Some 12 samples of wall papers of dif- 

 ferent color and quality were submitted to the test, and also lacquered 

 brass and a nickel-plated object. The fumigation chamber was un- 

 healed and was somewhat moistened from rains, and hence the air in 

 the room was at a fairly high degree of saturation, Avhich undoubtedly 

 very much increased the bleaching power of the gas. Practically all 

 the wall papers were considerably altered in color, either by notable 

 bleaching or by an actual change in the tone of color, in one case 

 becoming considerably darker than the original. The dark reds 

 were least affected — almost none — and the pinks and greens were most 

 affected. These tests indicated that the use of this gas would be very 

 apt to bleach wall papers in rooms or houses at all damp. With 

 houses subjected to regular heating, as in early fall or winter, the 

 bleaching probably would be reduced to a minimum. The lacquered 

 brass was unaffected. The nickel-plated object w^as badly rusted. It 

 was noted that in the damp weather which occurred at the time of 

 this experiment the wall papers retained an odor of the gas for a long 



