232 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 17 
dust form than either the granules or the flakes, as the hydrocyanic acid 
gas is given off more rapidly from the dust. 
During the past summer fleas were very plentiful in Missouri es¬ 
pecially through the central portion of the state, with the result that 
ample opportunity was offered to make some rather extensive tests with 
calcium cyanide. The credit for the work with fleas is largely due 
Mr. S. W. Bromley. This work was carried on in cooperation with 
the Department of Entomology of the Missouri Agricultural Experiment 
Station. 
The first test made was in a modern dwelling house in Columbia, 
Missouri on July 20, 1923. An Airdale dog was allowed to sleep on 
the second floor with the result that this floor became badly infested 
with the dog flea (Ctenocephalus canis Curtis). After the infestation 
was discovered the dog and two cats were kept out doors. The floors 
were new and of hard wood. The fleas were evidently in the rug, and 
upon entering this floor numbers of the pest would jump upon the 
trousers. No fleas were observed in any other part of the house. 
The house was fumigated with calcium cyanide flakes at the rate of 
4 ozs. to 100 cu. ft. on the second floor where the infestation was present, 
and one ounce per 100 cu. ft. on the first floor and the basement. The 
flakes were put down at 8:30 in the morning, the house emptied of its 
inhabitants and all the windows and doors closed. The flakes were 
scattered on newspapers on the second and first floor and on the concrete 
floor in the basement. Flakes were also scattered outside in the new 
sleeping quarters of the cats and dog, and the animals were treated 
with kerosene emulsion. 
At 5:30 P. M. the house was opened and the newspapers and flakes 
removed. The flakes were still giving off some gas. A number of dead 
fleas were shaken from the rug in the badly infested room. During 
the next few days three or four fleas were found in clothing which 
were evidently brought in from the outside. No further trouble was 
experienced and the owner was well satisfied with the results. 
Similar results were obtained in the basement of a store in Columbia, 
Missouri. The owner kept a dog in the basement and it became so 
badly infested that he feared the fleas would find their way up stairs 
and attack his customers. The basement was tightly closed and the 
door fixed so it could be opened from the outside. At 7:30 P. M., 
July 26, 1923, flakes were scattered on the concrete floor at the rate of 
two ounces to 100 cu. ft. The place was opened the next morning at 
