Jan. Feb. Mar. Apr. May June July Aug. Sept. Oct. Nov. Dec.
.6 5.1 5[D] ... 3 1.8 1.4 1.7 ... 1.1 2 2
(6) (11) (6) ... (6) (88) (26) (6) ... (8) (14) (2)
[Footnote D: This figure is high because one vole had the high number of
19 fleas. The numbers in parentheses show the number of live voles
examined for each month. All fleas were _Ctenophthalmus pseudagyrtes_
Baker.]
Some fleas have a habitat preference as well as a host specificity. As
voles from different areas were examined, different kinds of fleas were
encountered. A population of free-living voles under observation on the
Campus at Lawrence was parasitized only by _Ctenophthalmus
pseudagyrtes_. From 90 prairie voles collected in a field of clover 4
miles northwest of Lawrence, the only species of flea recovered was
_Orchopeas leucopus_. In both places the prairie vole was the most
common mammal, but in the field of clover three deer mice (_P.
maniculatus_) also were trapped. In a third field, one mile west of
Lawrence, the prairie vole was host to both the above mentioned fleas.
Here both the prairie vole and the cotton rat (_Sigmodon hispidus_) were
common.
The host distribution of fleas on seven small mammals which lived in the
same habitats as the prairie vole is given in table 6.
TABLE 6.--_Frequency of Occurrence of Fleas on Seven Species of Small
Mammals_[E]
Column headings:
A: _Cryptotis parva_
B: _Blarina brevicauda_
C: _Peromyscus maniculatus_
D: _Peromyscus leucopus_
E: _Sigmodon hispidus_
F: _Microtus ochrogaster_
G: _Pitymys nemoralis_
A B C D E F G
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_Orchopeas leucopus_ (Baker) 0 0 53 31 37 6 10
_Orchopeas howardii_ (Baker) =
_O. wickhami_ (Baker) 0 0 0 0 0 1 0
_Nosopsyllus fasciatus_ (Bosc) 0 0 0 0 0 1 0
_Epitedia wenmanni_ (Rothschild) 0 0 0 9 0 2 0
_Rectofrontia fraterna_ (Baker) 0 0 0 0 0 1 0
_Corrodopsylla hamiltoni_ (Traub) 47 8 0 0 0 0 0
_Ctenophthalmus pseudagyrtes_ Baker 0 38 0 0 4 25 53
_Peromyscopsylla scotti_ I. Fox 0 0 0 6 0 0 0
--------------------------
Total number examined 34 13 34 35 57 414 21
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[Footnote E: The numbers represent the percentage of each species which
was parasitized by fleas. The mammals were collected at Lawrence,
Douglas County, Kansas, between October, 1945, and June, 1946. These
data are entirely from snap-trapped animals with the exception of those
from _Microtus_ and _Pitymys_ which are from both snap-trapped and
live-trapped animals.]
It is seen that some fleas are rather specific in their choice of hosts,
and that others are commonly found on two or more small mammals in the
same habitat. In each of these groups there are fleas which have a
habitat preference, that is to say, the flea lives on the host when the
host lives in a given habitat, but is absent when the host lives in
another habitat.