HEMIPTERA. 181 
It seems hardly probable that it occurs in this country in sufficient 
numbers to cause much trouble on horses. Possibly examination of 
mules, asses, or donkeys would show greater abundance from the fact 
that horses in general are more carefully groomed than their somewhat 
despised relatives. The size is about the same as that of the ox louse, 
but it differs very decidedly in the form of the head, which is long, 
slender, and the sides of the head nearly parallel, as shown in the figure 
(fig. 103), taken from Comstock’s Introduction to Entomology. 
Careful grocming may be looked upon as at least favorable to the 
reduction of numbers in this species. In case they become too numerous, 
the application of a little kerosene to the card or currycomb used in 
grooming the animals will be found of value. Where more vigorous 
treatment is necessary, the measures recommended for the ox louse may 
be adopted. 
SUCKING LICE OF RODENTS. 
(Hematopinus spp). 
Belonging to the same genus of suctorial lice as those previously 
mentioned, we have a number of species common to the smaller main- 
mals, particularly those of the group of gnawing mammals, the Rodentia. 
These smaller mammals, though perhaps never strictly domesticated, 
save the rabbit, are very often kept in a semidomesticated state, either 
as pets in zoological gardens, or, in case of rats and inice, quite involun- 
tarily because of our inability to entirely rid ourselves of them. A few 
notes on the lice infesting them will therefore be of interest here. Itis 
desirable to be able to identify them in case of their accidental oceur- 
rence on other mammals, and thus be able to determine whether, in 
such cases, we have to deal with a species likely to prove troublesome. 
LOUSE OF THE RAT, 
The common rat (Jus decumanus) supports a species, Hematopinus 
spinulosus, which, with its host, must be distributed over most of the 
world. It has been taken at Ames, Iowa, though in small numbers, and 
it seems to be rather scarce. 
It is a small species of a light-yellow color, the head projecting very 
little in front of the antenne and the thorax very short. The mice are 
said to harbor a distinct species, but there seems to be some doubt as 
to its being a genuine species. 
LOUSE OF THE FIELD MOUSE. 
(Hematopinus acanthopus Burm.) 
Apparently common on our species of Arvicola, and does not appear 
to vary in any important particular from the descriptions of Europear 
specimens. 
It has been taken at Ames from a species of Arvicola. It resembles 
the preceding in color and form, but is somewhat larger. The sternal 
