6 BULLETIN 986, U. S. DEPARTMENT OF AGRICULTURE. 
Although never believing in the old vegetarian theory of the 
earlier entomologists, the writer decided to give this theory a test. 
First a minute examination was made of the blackberry plants, in- 
cluding all parts both in and above the ground. Nota single chigger 
was found on them. Then the examination was extended to the 
other plants growing on the vacant lots—goldenrod, several grasses, 
and a number of common weeds. Each plant species was taken by 
itself, specimens were pulled up, shaken over white paper, taken to 
the laboratory, and even examined in parts with the microscope. 
After several days of fruitless attempts to locate the larve feeding 
on plants the work was stopped, for evidently they could not have 
been feeding normally on these, or at least a few of their enormous 
numbers would have been encountered. 
About this time there appeared in this country the extensive paper 
by Drs. T. Kitashima and M. Miyajima (7) entitled, “Studien ueber 
die Tsutsugamushi-krankheit,” in which is given, among other 
things, a summary of the work on the life history and habits of the 
Japanese chigger, Zrombicula coarctata Berlese (1). These writers 
claimed to have reared this chigger mite from field mice and to have 
established the fact that it was normally parasitic on the same. A 
few days later Dr. Miyajima, who happened to be visiting in this 
country, called at the Bureau of Entomology while in Washington. 
During his stay he reiterated his statement that the Japanese chigger 
was normally parasitic on field mice and also said he believed that 
it normally parasitized various other mammals. 
Following the conference with Dr. Miyajima, it was decided, at 
once to investigate the small rodents which were known to exist in 
the vicinity and on the ground of the infested lots. A dozen traps 
were procured and trapping began with these on September 13 and 
continued until September 24. In all, traps were set in 21 different 
situations, including 13 in the infested area and 8 on adjoining unin- 
fested ground. Small mammals, chiefly rodents, were caught and 
examined microscopically in the laboratory as follows: 
Seplemberncjss. Sales 4 September 18________ 2 September 23_= ~___-_ “Al 
September 1p... 3 September 192 = 1 September 24________ 1 
September 16________ 1 September 20________ 1 
September 17____-___ 2 September 22. --. = aL 
Tn all, 17 small mammals were caught, all within 11 days. Among 
those obtained the following were determined by Dr. Ned Dearborn, 
of the Bureau of Biological Survey: House mouse (M/us musculus) ; 
common meadow mouse (A/icrotus pennsylvanicus) ; short-tailed 
shrew (Slarina brevicauda). 
Not only were the skins of these mammals examined carefully, but 
the ears and some of the other parts were removed and washed 
violently in alcohol and the washings examined. As a result of these 
examinations not a single chigger was found. 
re panda a af 2 
