EXPEEIMENT STATION REPORT. 651 



it has been found that twenty minutes' exposure is sufficient to kill 

 mosquitoes, it will be better to allow rooms to remain closed tightly 

 at least an hour after the material has completely evaporated. The 

 quantity given, three ounces to 1,000 cubic feet of space, presup*- 

 poses a moderately tight room, to be fumigated. If doors or win- 

 dows are leaky an excess should be used, and in large cellars, for 

 instance, two or three fumigators are better than one to secure more 

 rapid evaiX)ration. 



The entire outfit exclusive of the lamp, but including the charge 

 of the tinman for cutting and punching the pipe, was forty cents. 

 The actual outlay need not be over fifteen cents. Wood or dena- 

 turized alcohol will answer eveiy pur}X)sei, so that the cost of the 

 fumigating outfit is very small. 



KillarvsB. 



This is a preparation consisting of two powders which, when 

 united in the presence of water, ev^olve or form ammonia. The 

 water becomes more or less charged with this ammonia, in pro- 

 portion to the amount of material used, and it is given off from 

 the surface, as the very decided odor proves. 



The preparation comes from the Nienstadt Laboratory, at Ho- 

 boken. New Jersey, and a sample was sent in for trial in May, 

 supplemented later by a jDurchased lot, to be tried on a more 

 extensive scale. 



Quite a number of laboratory experiments and experiments on 

 small areas were made, but condition proved adverse when a large 

 area was undertaken, at Barnegat, a brood having just come out 

 of the pools and the water being clear at the time. 



July 10th and 11th, applications were made to some lot pools 

 containing larvae of C. pipiens and C. jaofnaicens'is at vaiying 

 strengths, from that recommended on the packages to a concen- 

 trated mixture. The result of these experiments was, on the whole, 

 unsatisfactory, and on July 18th the experiments v/ere repeated, 

 with Dr. A. E. Nienstadt, the inventor of the compound, in 

 attendance. Four lot pools Avith large numbers of wrigglers were 

 treated, and into each a large amount of the mixed powders was 

 stirred. The pools varied in size and the ammonia odor was 

 obvious in all cases. Check experiments were also carried on in 



