2 
‘ 
have until recently been commonly attributed to “chiggers,”’* which 
inhabit neither the dried straw nor thrashed grain. The term “chig- 
ger’’ really includes a number of different kinds of mites, notably the 
young of Trombidium and other insects which inhabit grassy and 
weedy places and woodlands. This is why it is that people visiting 
such places are not infrequently attacked and suffer painfully there- 
from. While our knowledge of the matter remained in this condi- 
tion, the possibility of confusing the disease discussed herein with 
others of a much more serious nature was very great, but now that 
we understand the causes and know that these causes can be re- 
moved, and the physician enabled to distinguish it from an attack 
of ‘“‘chiggers”’ and prescribe proper treatment, much of this danger 
and painful annoyance may 
be eliminated. There is also 
another point that must not 
be overlooked, namely, that 
this mite during its period of 
greatest activity is almost in- 
visible to the unaided eye (see 
fig.1). Not every practicing 
physician possesses a micro- 
scope that will enable him to 
detect the presence of the 
mite, even when abundant, 
but the pustules or wheals 
caused by it are sufficiently 
described in the paper by Doc- 
tors Goldberger and Scham- 
berg and the one by Doctor 
Rawles to permit of identifica- 
tion. Later, when the gravid 
Fig. 2.—Gravid female of Pediculoides ventricosus. Greatly female mite (fig. 2) is dis- 
enlarged. (Redrawn from Brucker. ) 
tended with eggs and young, 
it is more easily detected; but it is not in this state that it attacks 
human beings and is thus encountered by the practicing physician. 
THE MITE BENEFICIAL IN AMERICA. 
So far as the author has been able to determine, the first pub- 
lished record of the occurrence of this mite in America was by him- 
self, and was included in a paper printed in the Twelfth Report 
of the State Entomologist of Ilinois (pp. 150-151). While assistant 
to Dr. S. A. Forbes, state entomologist, he was directed to investi- 
gate serious injuries to stored grain by the Angoumois grain moth, 
a For a consideration of ‘‘chiggers,’’ see Circular No. 77, Bur. Ent., pp. 1-6. 
b Published in Trans. Dept. Agr. Illinois, vol. 20, 1882. 
[Cir. 118] 
