106 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 6 



4. Stomoxys is distinctly more abundant under rural conditions, 

 than in cities and thickly populated areas. 



5. While the disease spreads over districts quickly and in a rather 

 erratic way, it often appears to follow along lines of travel, and it is 

 known that Stomoxys flies will often follow horses for long distances 

 along highways. 



6. In a surprisingly large number of cases, it appeared probable 

 that the children affected had been in the habit of frequenting places 

 where Stomoxys is particularly abundant, i.e., about stables, barn- 

 yards, etc. 



During the summer of 1911, 88 cases of poliomyelitis were visited 

 and studied both with regard to the individual histories of the patients 

 and to the insect fauna of their environment. Stomoxys was found in 

 every case, and often in exceptional abundance, while nothing appeared 

 which would cast doubt upon a possible association of this insect with 

 the disease. 



The suspicion attaching to Stomoxys seemed to be strong enough 

 to warrant direct experimentation, and during the past summer Prof. 

 M. J, Rosenau of the Harvard Medical School and the present writer 

 attempted to ascertain by experiments with monkeys whether the 

 virus of poliomyelitis could actually be transferred by Stomoxys 

 under controlled laboratory conditions. For this purpose a large cage 

 was constructed of light wood, with a flat wooden base about four by 

 five feet in size, with sides three feet in height. The sides and a part 

 of the top were covered with ordinary screen wire, a strip one foot wide 

 being left along one side of the top. The inner walls were further 

 lined with surgeon's gauze to afford a resting place for the flies, and 

 the open part of the top provided with a large black cloth which could 

 be lifted to give access to the interior of the cage. Specimens of Sto- 

 moxys were collected daily in amounts of from 300 to 500 and ad- 

 mitted to the cage, so that in spite of the high mortality among the 

 flies thus caged, a thousand or more were continually present. A 

 healthy monkey was now infected with poliomyelitis by inoculation 

 in the brain with a lethal dose of active virus of the disease. The 

 virus in this case was obtained by making an emulsion of bits of spinal 

 cord from monkeys which had died of the disease after being similarly 

 infected; it had come originally from a human case of the disease, but 

 had been later passed through a number of monkeys, as can be done 

 without impairing its virulence. This monkey was then exposed to 

 the captive flies daily, by stretching it at full length and rolling it in 

 a piece of chicken wire, then placing it on the floor of the cage. Such 

 treatment was necessary as the agile monkey would otherwise soon 

 have demohshed the frail cage. The Stomoxys fed on it freely during 



