18 
surrounding country in epidemic form. Through the press notes it 
seemed to be quite general over the northern part of the United 
States, limiting itself to the wheat-growing sections. 
The people generally affected were farmers and those living in 
small villages or towns where straw is used in beds, under carpets, and 
around stables to bed stock. Horses and cattle have been seen with 
a skin disease almost identical with that seenin man. The following 
incident led him to an investigation as to the probable etiology: 
A family had cleaned house, refilled the straw ticks of their beds, 
and placed fresh straw under the carpets, and in about one week the 
family had developed this peculiar skin disease. In the beds was 
found a small black fly (/sosoma tritict Fitch) about the size of an 
ordinary gnat, which at first 1t appeared to be, but closer observation 
revealed that it was not of the gnat family. Upon examination of the 
straw it was found that a large number of the straws were perforated; 
these perforations were through the wall in the region of the joint, 
generally about 2 inches from the joint. The perforations were about 
the size of a small pinhole and ranging in number from ten to thirty in 
a straw. Upon examining a section of this straw the small black fly 
was found under many of the openings through the walls. 
Several flies were examined to ascertain if they possessed a piercing 
proboscis, and while observing one which had just been taken from 
under the sheath of the straw, through which there was no perforation 
over the fly, a small mite was observed crawling over the dead body 
of the fly. 
Placing the bodies of several of these flies under the microscope and 
using a one-fourth-inch objective and a No. 5 eyepiece, it was found 
that on nearly all flies over which the wall was intact a small mite 
could be detected, these varying in number from two to four mites to 
each fly. Upon furthering the observations it was found that the 
dermatitis lasted after the flies had been observed and exterminated. 
The following experiments were tried to prove whether it was the 
fly or the mite that was the etiologic factor in producing the dermatitis. 
Six live flies were taken, upon which no mites could be found; 
these were placed under a watch glass and bound upon the right arm, 
leaving them in contact with the skin for three hours. Upon the left 
arm four dead flies, on which living mites had been observed, were 
placed under a watch glass and left in contact with the skin for three 
hours, after which the glasses were removed and results awaited. 
The right arm showed nothing. Upon the left arm there appeared 
within twelve hours four small wheals, the character and evolution of 
which are later described. 
To further the experiments some fresh lesions of patients were 
scraped and the scrapings examined microscopically, and two of the 
mites were found in the scrapings. 
[Cir. 118] 
