| 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) |
[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 | |
| 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 |
[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.