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SPATE OF ILLIENOUS
William G. Stratton, Governor

DEPARTMENT OF REGISTRATION AND EDUCATION
era M. Binks, Director

ECTOPARASITES OF THE
COTTONTAIL RABBIT

In Lee County,
Northern Illinois

Lewis J. Stannard, Jr.
Lysle R. Pietsch

ATURAL HISTORY Btoloa}

gical Notes No. 38
URVEY DIVISION Printed by Authority of the State of Illinois
arlow B. Mills, Chief Urbana, Illinois June, 1958

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Ectoparasites of the Cottontail Rabbit

In Lee County, Northern Illinois

Of the wild animals in Illinois, the eastern cotton-
tail rabbit, Sylvilagus floridanus mearnsii (Allen), is
the species most commonly hunted and handled by
human beings. Because rabbits are carriers of the viru-
lent disease tularemia, which is transmitted from rabbit
to rabbit by certain ectoparasites and from rabbits to
men by handling, the ectoparasites of these animals
are of considerable importance to human beings as
well as to rabbits.

A few years ago, ectoparasites of Illinois cotton-
tails received limited investigation by Ecke (1948) and
by Ecke & Yeatter (1956). About the same time, Yeatter
& Thompson (1952) published an analysis of rabbits,
their ectoparasites, and their diseases in relationship
to weather and man. These studies served to bring new
attention to the many gaps in knowledge of the seasonal
activity and abundance of the ectoparasites of rabbits.

When an opportunity arose in 1952 to make further
observations on rabbits and their ectoparasites as part
of a larger study of management of cottontails, a study
designated as Project No. 42-R and set up under terms
of the Federal Aid in Wildlife Restoration Act,t the
authors joined forces in the hope that some new facts
might be discovered that would fill one or more of these
gaps. We realized that only part of our time could be
devoted to this work and that our treatment necessarily
would be brief. Principally, we hoped to learn the exact
period in the year rabbits are free of ticks and conse-
quently free of tularemia. We learned this and more.
We noted unsuspected behavior patterns of the adult
continental rabbit tick (//aemaphysalis leporis-palustris),
seasonal fluctuations of the common eastern rabbit flea
(Cediopsylla simplex), and additional facts concerning
these and other ectoparasites. Herein is the report of
our observations and of the collections on which they
were based,

Acknowledgment is made to Drs. Harlow B. Mills,
Herbert H. Ross, Thomas G. Scott, Ralph E. Yeatter,
and Carl O. Mohr, Mrs. Leonora K. Gloyd, Mrs. Diana
R. Braverman,. and James S. Ayars, all of the Illinois
Natural [listory Survey, for advice concerning inter-

* Associate Taxonomist, Illinois Natural History Survey.

T At time of study, Game Biologist, Illinois Department
of Conservation.

tThe Illinois Department of Conservation, the United
States Fish and Wildlife Service, and the Illinois Natural His-
tory Survey, co-operating.

Lewis J. Stannard, Jr.,* and Lysle R. Pietsch}

pretations and presentation of the data. Identification
of some of the fleas was made or confirmed by G. P.
Holland of Ottawa, Ontario. The photographs were taken
by William IE. Clark of the Illinois Natural History
Survey. We are indebted to Glenn I]aas, who has made
a similar study in Wisconsin, for suggestions and con-
structive criticisms.

SCOPE OF STUDY

Field work was conducted near Amboy, Lee County,
on farm lands and idle fields, many of them similar to
the field shown in fig. 1. Lee County is typical of most
of northern Illinois. Here rabbits from two areas, each
of about ] square mile, were examined. One area con-
sistently had a much higher average per-acre population
of cottontails than the other. The area with the greater
number of rabbits yielded a greater number of ectopara-
sites. In this report, data from the two areas are combined.

Most of the rabbits examined were trapped alive,
examined alive, and released. The ectoparasites were
removed in the field, often as late as several hours
after the rabbits were captured. Undoubtedly some
ectoparasites were missed, such as those deep in the
ears, but probably a large majority of the ticks and fleas
were taken. Presumably not enough were overlooked to
alter our conclusions appreciably. Nevertheless, the
reported percentages of rabbits infested by each species
of ectoparasite and the average numbers of ectoparasites
per rabbit should be regarded as minima.

The junior author collected over 10,000 ectopara-
sites from more than 700 rabbits in the period beginning
May, 1952, and ending November, 1954. Collecting varied
in intensity according to the time that could be given
to the study. The senior author sorted, identified, and
counted the ectoparasites.

Occasionally a rabbit was caught several times-
within a season. For example, a rabbit designated as
Peter II was caught nine times in July and August,
1952, and each time all the ectoparasites found on it
were removed and preserved. Other rabbits, No. 57 and
No. 307, were caught five times each; several were
caught four times; and as many as 30 were caught two
or three times within a 2-month period.

Additional
Illinois (Jackson and Union counties) was gathered by
Dr. Willard D. Klimstra of Southern Illinois University

material from rabbits from southern

and Glen C. Sanderson, the latter employed jointly by
the [llinois Department of Conservation and the Illinois
Natural
with those gathered from many other areas by Survey

History Survey. These collections, together

staff members, were compared with the data obtained
from Lee County in northern Illinois to secure informa-
tion on the differences in the seasonal behavior of
rabbit ectoparasites within the various climatic zones
of Illinois. Illinois, a long state, extends about 380
miles from north to south and embraces several climatic
and life zones.

Cottontails in Illinois are the normal hosts to at
least seven species of facultative or obligate ectopara-
sites, exclusive of chiggers and other small mites. In-
frequently, perhaps accidentally, rabbits of Illinois may
acquire other species of ticks and fleas that regularly
feed on other mammals, such as ground squirrels, mice,
and moles, but these ectoparasites do not usually per-
sist on rabbits.

Rabbits in the western part of North America are
hosts to several more, most of them different, species
of ectoparasites than are rabbits in the eastern part,
table 1. Often where one species of ectoparasite drops
out at the edge of its range, another biologically equiv-
alent species takes over and continues into the adja-
cent geographical range. There is a sudden change in
the kinds of species of ectoparasites on rabbits at
about the 100th meridian. Cottontails in Illinois are
infested by every rabbit ectoparasite known. east of the
100th meridian except the flea //oplopsyllus (Euhoplo-

psyllus) glacialis affinis (Baker). To date, no speci-
mens of affinis have been taken in Lee County or else-
where in Illinois.

TICKS

Haemaphysalis leporis-palustris (Packard); conti-
nental rabbit tick, rabbit tick; fig. 2. When ranked ac-
cording to numbers of individuals collected within a
period of a year, the continental rabbit tick stands as
the principal ectoparasite of cottontails in Illinois.
This tick is also apparently the chief carrier from rabbit
to rabbit of the organism, Pasteurella tularensis, that
produces tularemia, a disease which is invariably fatal
to rabbits (Green 1939).

Although the continental rabbit tick is common over
much of North America and all of Illinois, fig. 3, and is
collected frequently by biologists, many aspects of its
life history are poorly known.

We found and others have reported that individuals
of this tick feed mostly on the rabbit’s head, particularly
on and in the ears, on the back of the neck, and some-
times around the eyes and nose and under the chin.

Hooker et al.(1912) were among the first to publish
detailed biological information on this tick. According
to their findings in Texas, ‘‘The three stages of the
rabbit tick have been taken from hosts in nature during
all seasons of the year.’’

According to a number of authors, the continental
rabbit tick in areas north of Texas, specifically in Okla-

Table 1.—Distribution of the common ectoparasites of rabbits in the United States, exclusive of chiggers,

small mites, and nest inquilines.

Species Found East of

Group 100th Meridian

Haemaphysalis leporis-palustris
Ixodes dentatus

Haemaphysalis leporis-palustris
Ixodes spinipalpis

Species Found West of 100th Meridian

Haemaphysalis leporis-palustris
Ixodes neotomae

Hoplopsyllus glacialis affinis

Ticks Dermacentor variabilis Dermacentor andersoni Dermacentor parumapertus
Otobius lagophilus Ornithodoros turicata

Cediopsylla simplex Cediopsylla inaequalis Cediopsylla inaequalis

Odontopsyllus multispinosus Odontopsyllus dentatus Odontopsyllus dentatus
Fleas Hoplopsyllus glacialis affinis Hoplopsyllus glacialis affinis

(Apparently rare east of Missis- Hoplopsyllus foxi

sippi River; taken from imported

Kansas cottontails in New Jersey,

Burbutis & Mangold 1956)

+—

Cuterebra buccata Cuterebra leporivora Cutere bra leporivora
Bot Cuterebra horripilum Cuterebra lepusculi Cuterebra lepusculi
Flies Cuterebra cuniculi
Lice

Haemodipsus setoni

Haemodipsus setoni

Fig. 2._Haemaphysalis leporis-palustris, continental rab-
bit tick, unengorged adult female. This tick is a vector of tu-
laremia. The characteristic of sharply pointed, lateral angles
near the base of the mouthparts (one indicated by arrow) is
distinctive of this tick in all stages.

homa, Missouri, Iowa, Montana, and Minnesota, is not
equally abundant on rabbits at all seasons, and, further-
more, one or more of the stages are often rare to absent
at certain seasons. Even in Florida the continental
rabbit tick is noticeably less abundant in winter (Ilixon
in Eddy 1942).

Apparently the more northerly the region the more
markedly the populations of this tick fluctuate on rab-
bits with the seasons. In Oklahoma (Eddy 1942) and in
southern Missouri (Portman 1944), this tick occurs
occasionally on rabbits even in midwinter. By contrast,
in northern Missouri (Portman 1944), Iowa (Joyce &
Eddy 1943), Montana (Cooley 1932), and Minnesota
(Green et al. 1943), it becomes scarce on or entirely
absent from rabbits during the coldest winter months.

In Minnesota, Green et al. (1943) found that larvae
of Haemaphysalis leporis-palustris ‘‘suffer a relatively
enormous loss as compared with the losses among older
ticks, and that the total winter mortality can be ac-
counted for largely on the basis of deaths of larval
ticks.’’ In Iowa, Joyce & Eddy (1943) reported an abrupt
decrease to very few larvae on rabbits in November, an
absence of larvae in December, and a low prevalence of
larvae on rabbits in April, May, and June. Apparently
in Iowa, as in Minnesota, many unfed larvae fail to
survive the winter.

Hooker et al. (1912) observed that under favorable
conditions ticks in the larval stage could survive as
long as 258 days (about 8 months) without feeding. They

found, however, that most larvae survived for 2 to 7
months.

In this study, we found that continental rabbit ticks
came out of hibernation earlier in southern Illinois than
in Lee County. An observation of winter activity was
made by Glen C. Sanderson in Union County, southern
Illinois. There he found, on December 21, 1955, an adult
rabbit tick feeding on a swamp rabbit, Sylvilagus aquat-
icus aquaticus (Bachman). In southern Illinois, adults
appeared regularly in some abundance on rabbits at the
end of January. Our earliest records of the year for
rabbit ticks in Lee County were of adults collected on
February 25, 1953, and February 17, 1954.

When the warmer weather of spring arrived, increas-
ing numbers of both adults and nymphs of the continental
rabbit tick were found attached to rabbits in Lee County,
fig. 4. By mid-April copulating pairs were observed on
their hosts. By July the numbers of adults had decreased.
Adults seldom were found on rabbits in Lee County in
autumn or the first part of winter. Only one adult was
found on these rabbits in fall. This specimen was taken
on November 9, 1954. Although rarely on rabbits in
autumn and winter, adults were present in the surround-
ings and were taken repeatedly in September, October,
and November from leaf mold.

During the several winter and spring months in
which we examined rabbits for ticks in Lee County, we
found no larvae of the continental rabbit tick. We learned,

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Fig. 3.—Haemaphysalis leporis-palustris distribution in
Illinois, based on Illinois Natural History Survey records.

vu

however, of a record of larvae from a towhee, Pipilo
erythrophthalmus, collected on May 14, 1951, at Zion,
a northeastern Illinois town near the Wisconsin border.
Dr. S. Charles Kendeigh, an ornithologist at the Univer-
sity of Illinois, believed that, because of the late date,
this towhee was a resident bird and had not recently
arrived. It is possible that the towhee acquired the
ticks at Zion rather than from some southern area.
Seemingly, the larvae on the towhee survived a northern
Illinois winter in an unfed condition. Larvae began to
appear on rabbits in Lee County in the latter half of

July or in August, table 2 and fig. 4. We have records
of one earlier appearance, on June 25, 1954, in Lee
County and one on July 5, 1946, in central Illinois,
(INHS collection*). Larval ticks reached the peak of
their abundance on rabbits in Lee County in August and
September. Heavy concentrations of larvae on rabbits
ended abruptly in late October or early November, their
disappearance coinciding with the beginning of deep
frosts and colder weather.

*|llinois Natural History Survey collection, Natural Re-
sources Building, Urbana, Illinois.

Table 2.—Number of larvae, nymphs, and adults of the continental rabbit tick, Haemaphysalis leporis-palustris, taken from
cottontails examined in Lee County, Illinois; also, the average number of each stage of the tick per rabbit examined.

I Number Average Number of Ticks
of Number of Ticks Taken Per Rabbit Examined,
Month Year Rabbits 195 2—1954
Examined [Larvae | Nymphs Adults Larvae Nymphs Adults
January 1952 = - = -
1953 9 0 0 0 0.0 0.0 0.0
1954 1 0 0 0
February 1952 ~ _ - -
1953 113 0 0 1 0.0 0.0 0.1
1954 40 0 0 20
March 1952 — _ — -
1953 1l 0 89 123 0.0 8.0 11.2
1954. = = = me
April 1952 - = = =
1953 5 0 14 133 0.0 2.8 26.6
1954 = = Es =
May 1952 4 0 2 6
1953 12 0 195 104 0.0 123) 6.9
1954 — - _— _
June 1952 52 0 36 221
1953 9 0 17 142 0.01 1.5 6.7
1954 6 1 50 87
July 1952 13 0 0 2
1953 63 852 26 17 10.6 0.4 2.5
1954 4 0 6 23
August 1952 15 260 39 3
1953 8 173 5 7 19.6 4.0 0.4
1954 &) 116 69 2
September 1952 77 2,433 922 1
1953 _ — - — 31.6 12.0 0.01
1954 _ = i es
October 1952 74 i 64
1953 72 388 957
1954 19 117 146
November 1952 37 6 ll
1953 38 21 63
1954 26 11 15
December 1952 = = a
1953 2 0 0
1954 = = =
TOTAL (eae | 4,385 [ 2,726

AVERAGE NUMBER PER COTTONTAIL

OLS XX

S
> a. sane Pe o

Fig. 4.—Monthly average of larvae, nymphs, and adults of Haemaphysalis leporis-palustris found on rabbits examined in
Lee County, Illinois, 1952-1954. The graph is based on data in table 2.

Nymphs of the year appeared on Lee County rabbits
from about the middle of August until about the middle
of November, table 2 and fig. 4. They became most
abundant in September and the first half of October. Like
the larvae, the nymphs became scarce and disappeared
from rabbits at the onset of cold weather, but, unlike
the larvae, the nymphs commonly survived the winter in
a state of hibernation and reappeared on rabbits in the
spring. August 1, 1953, was our latest seasonal record
for a nymph presumed to be of a generation started in
the previous year. Because nymphs eventually transform
into adults or perish, it is not surprising that a decline
in the numbers of nymphs collected occurred in June.

Illinois seems to be wholly in the region wherein
continental rabbit ticks are generally absent from rab-

bits in winter. In Lee County we did not find ticks on
rabbits in December, January, or most weeks of Febru-
ary, table 2 and fig. .4. In southern [Illinois we have a
few records of limited winter activity. We have no rec-
ords, from any part of the state, of ticks being on their
hosts during most weeks of January, the coldest month
of the year. On the other hand, it is probable that during
warm winter spells some of these ticks, especially
those in southern Illinois, may be quick to come out of
hibernation to feed.

If it were not for literature records of larvae sur-
the
possibly even Alaska (Philip 1939), we would have

viving winter in Montana, Minnesota, Iowa, and

suspected from our data that extremely few larvae of
the continental rabbit tick can overwinter in northern

Illinois. Although some larvae survive, winter cold may
take, directly or indirectly, a heavy toll of unted larvae.

Apparently, some larvae do not survive much more
thana few months in anunfed state (Hooker et al. 1912).
Because the larvae in Lee County are probably at least
2 months old by late fall, many of those that have not
found a host before the beginning of winter may be sup-
posed to perish from starvation. The nonlethal starva-
tion period possible for most larvae may terminate at
about the time temperatures drop in winter. At this
time larvae, numbed by cold and unable to seek a
host, may die from lack of food rather than from cold
directly. The extent to which cold alone or combined
with other factors may adversely affect unfed larvae
is an unsolved problem that is worthy of future in-
vestigations.

Low temperatures may influence adults as well as
larvae. Adults of the continental rabbit tick, in both
the north and south, go into hibernation or into a period
ofrest even before the advent of cold weather. Possibly
they require a period of rest or subjection to low temper-
atures before they are able to feed, mate, and lay eggs.
Such seems to be the case with adults of the eastern
rabbit tick, [Ixodes dentatus, which, according to Smith
(1945), must undergo hibernation in the unengorged state
for one winter before they will feed. Similar behavior
may be inherent in the continental rabbit tick. If so,
the termination of this rest period may come about during
the winter. Because of a longer period of low tempera-
tures in the north, adults there would necessarily wait
longer before seeking a new host than would adults in
the south. We made no observations on whether the
photoperiod affected the activity of the adults.

It is presumed that in Lee County most rabbits
become hosts to rabbit ticks at some time, if not many
times. For example, between August 1] and August 30,
1952, one rabbit, designated as Peter II, was infested
with at least 60 ticks in the following sequence: August
ll, 6 ticks; August 18, 13 ticks; August 21, 11 ticks;
August 22, 0 ticks; August 25, 10 ticks; August 27,
14 ticks; and August 30, 6 ticks. Other rabbits may
encounter continental rabbit ticks as frequently as did
Peter II.

The proportion of rabbits in Lee County infested
with the continental rabbit tick varied greatly with the
season. During the period of greatest tick abundance,
August and September, nearly 90 per cent of the rabbits
examined had one or more ticks. By contrast, from late
fall through the coldest part of winter, almost no rab-
bits harbored ticks. In late spring nearly 75 per cent of
the rabbits examined had ticks. In June, the number of
infested rabbits dropped to 50 per cent or less. The
number dropped again in late October and dwindled to
almost: zero by mid-November.

A larger number of larvae than nymphs and a
larger number of nymphs than adults were found on rab-
bits in Lee County. Each tick must find a host three
times during its life, and the decline in numbers of ticks
between stages may be directly correlated with the
chances involved in procuring hosts.

Larvae and nymphs of the continental rabbit tick
often select ground-inhabiting birds as alternate,
possibly equal, hosts. Adults of this tick rarely occur
on birds; instead, they prefer rabbit hosts almost ex-
clusively (Bishopp & Trembley 1945). Our records for
for larvae and nymphs include such bird hosts as brown
thrasher, towhee, prairie chicken, olive-backed thrush,
tufted titmouse, quail, and swamp sparrow. Birds have
been found infested as early in the year as April in
central Illinois and as late as December in southern
Illinois (INHS collection). Undoubtedly, migrating birds
are responsible for dispersing some of these rabbit
ticks northward in spring and southward in fall.

Dermacentor variabilis (Say); variable wood tick,
wood tick, American dog tick; fig. 5. — Insofar as num-
bers are concerned, the variable wood tick is a minor
ectoparasite of rabbits. In Illinois it is the principal
vector of Rocky Mountain spotted fever in man. The
relationship of this tick to rabbits, to the disease
organism that produces spotted fever, and to man is
undoubtedly an important one. Price (1954) recently
stated that the strains of Rickettsia virus that cause
Rocky Mountain spotted fever in man are maintained in
nature primarily in ticks of the genus Dermacentor rather

Fig. 5.—Dermacentor variabilis, variable wood tick, un-
engorged adult female. This tick is a vector of Rocky Moun-
tain spotted fever. [t was rarely found as an adult on rabbits
in Lee County, Illinois, 1952-1954. In the immature stages, ~
which were occasionally found on rabbits in Lee County, it
can be distinguished from other Illinois rabbit ticks by the
presence of eyes.

than in ticks of the genus Haemaphysalis. In contrast
to the continental rabbit tick, which rarely bites man,
the wood tick readily bites and engorges on man. In
fact, the wood tick is the only tick in Illinois that is
likely to attack a human being.

Larvae and nymphs of this tick prefer mice as
hosts, although, in some areas and under certain con-
ditions, rabbits are said to be important hosts for the
immature stages (Eddy & Joyce 1944). Portman (1944)
recorded that in southern Missouri larvae occur on rab-
bits in spring and even as early as January or February.
Adults, which are not found frequently on rabbits (Smith
et al. 1946), prefer larger mammals, for example, dogs
(formerly, in all probability, coyotes and wolves), deer,
raccoons, and opossums.

In Lee County, larvae and nymphs of the variable
wood tick were found to infest rabbits, but only in lim-
ited numbers. Larvae were taken in May and nymphs in
June and July. No adults were collected from any of
the rabbits examined.

The reason the variable wood tick is associated
in the early stages with rabbits, but not usually with
them as a mature tick, is unknown at present. If it is
not a matter of direct sensory reaction, it may be that
the movement patterns of the adult tick and the rabbit
do not coincide. Adults of this tick move to the edges
of broad, bare pathways (large-animal trails) and roads
(Smith e¢ al. 1946) and climb the overhanging vegetation
to await a host. It could be presumed, therefore, that
only animals that frequent such avenues of travel would
be apt to become infested by adults. Seemingly, rabbits
do not often use pathways made by larger animals and,
according to Stone & Cram (1902), they follow their own
narrow runways. Furthermore, when rabbits come out to
roadsides, they may not regularly move close to the
overhanging grasses and herbs where the adult ticks
wait. By contrast, dogs, wolves, and other large mam-
mals are said to follow large-animal trails habitually
and may often brush against the vegetation that har-
bors ticks.

Larvae and nymphs of the variable wood tick occur
mostly away from roadsides and paths, according to
Smith et al. (1946), and, although they usually select
mice as hosts, they occasionally feed on rabbits.

Ixodes dentatus Marx; eastern rabbit tick; fig. 6. —
As recently as 15 years ago, the eastern rabbit tick
had not been reported from areas west of the Appala-
chian Mountains (Bell & Chalgren 1943). Cooley &
Kohls (1945) gave the first midwestern record, a single
female from Ames, Iowa. Ecke & Yeatter (1956) report-
ed on the first Illinois specimens. We now have an
additional Iowa record, a specimen from Edron, col-
lected by Dr. Thomas G. Scott, and nine locality rec-
_ords from Illinois, fig. 7.

Fig. 6.—/xodes dentatus, eastern rabbit tick, unengorged
adult female. Adults of this species may be distinguished from
adults of the other rabbit ticks in Illinois by the relatively
long mouthparts (palps, indicated by arrow) and lack of scal-
lops (festoons) around the posterior dorsal margin of the body.
Determination of the immature stages can be made by using
the key published in Cooley & Kohls (1945).

ja Se ot
f
( ee
\ i j
\ Hh
ale Sa Ho
f a z
pe oo /
¢ fe
3 jee 5
{_ b—-4 ie ye
\ pel - 2
\ a ;
K j
\ {
{
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)) e
J e
wT~, ene
f
f 1 j
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7 e
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e n
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Fig. 7.—/xodes dentatus distribution in Illinois, based on
Illinois Natural History Survey records.

The life history of this tick was studied by Smith
(1945) in Massachusetts. He found that, in the eastern
United States, larvae hatch in July and August; that
many of them and some of the resultant nymphs feed
in the fall and hibernate through the winter; that those
larvae and nymphs that do not feed in the fall feed in
the spring and eventually transform into adults; and
that fall-produced or spring-produced adults must under-
go hibernation through a winter before the final feeding,
mating, and egg laying can take place. Smith did not
find this tick on rabbits in January or February. The
seasonal cycle of this tick may be similar to the cycle
of the continental rabbit tick.

The eastern rabbit tick is found to be fairly common
on rabbits along the northeast Atlantic Coast. There,
like the continental rabbit tick, it may occasionally
attach to birds and sometimes, perhaps accidentally,
to other mammals (Smith 1945).

This tick proved to be rare in Lee County. In our
study, it was found on three rabbits: adults and larvae
on two cottontails caught on May 8, 1953, and adults
on one cottontail caught on June 4, 1954.

In the southern tip of Illinois, in 1934, Dr. Herbert
H. Ross found nymphs and larvae active on rabbits as
late as December 5.

Ixodes sculptus Neumann; ground squirrel tick. —
This tick is found primarily on ground squirrels and
only incidentally on rabbits. It was recorded once in
Illinois on rabbits from the central part of the state
(Ecke 1948). We did not find it on rabbits in Lee County.

FLEAS

Cediopsylla simplex (Baker); common eastern rab-
bit flea; figs. 8 and 9. — The common eastern rabbit
flea is the second most numerous ectoparasite of cot-

Fig. 8.—Cediopsylla simplex,common eastern rabbit flea, adult female. The presence of a heavy comb of toothlike spines
below the eyes distinguishes this species from Odontopsyllus multispinosus.

10

tontails, second only to the continental rabbit tick.
Unlike the tick, which is generally absent in the winter,
this flea is present on rabbits throughout the year in
Lee County.

The life cycle and the numbers of generations of
this flea per year are virtually unknown. Ewing & Fox
(1943) stated that one specimen, reared in a vial, passed
from the larval stage into the adult stage in less than
3 weeks in the month of April.

In general, the common eastern rabbit flea tends
to concentrate on the rabbit around the area of the ears.
It occurs also on the face, top of the head, and back of
of the neck. In rare instances, this flea was found on
the back, and occasionally it was taken from some
other part of a rabbit’s body.

Although we examined rabbits during only one
entire spring season (1953), and our results should be

checked against other collections made in the spring
from a greater number of rabbits, perhaps it is worth
while to note that a springtime increase of fleas of
this species seems to occur on rabbits, fig. 10. In
February, 1953, the average number of these fleas per
rabbit infested had risen above the average number
found in the preceding summer and fall. In March of the
same year, a sharp increase in average number per rab-
bit occurred on the ]] rabbits examined. These fleas
continued to be abundant during April and May on most
of the small number of rabbits examined, table 3. For
the entire study, the percentage of rabbits carrying
these fleas was highest in the period beginning in No-
vember and ending in May and lowest in midsummer,
table 3 and fig. 10.

Approximately 3,000 specimens of the common
eastern rabbit flea were collected from rabbits in Lee

Fig. 9,.—Cediopsylla simplex, adult male. In this sex, part of posterior protrudes conspicuously.

County. Of these, 1,882 individuals were females and
1,060 were males. This distribution of the sexes gives
a ratio of 100 females to 56.3 males, or about 2 females
to 1 male. Month by month, the ratio remained about the
same. The number of males and females carried on any
one rabbit varied from many females per male to more
males than females. However, when the total popula-
tion of fleas present on rabbits each season was con-
sidered, the same 2-to-] ratio was observed, even in
the springtime when the fleas were suspected to be most
actively breeding. Shaftesbury (1934) found a similar

ratio of sexes, 100 females to 56.1] males, for this flea
in North Carolina. His figures are based on a small
number of specimens, 189,

The highest number of common eastern rabbit fleas
found on one rabbit was 101, collected March 25, 1953.
This case was considered unusual; a few other rabbits
harbored 70, 80, or even 90 fleas each, but most were
less heavily infested. The average number of these
fleas per rabbit examined was approximately 4. Some
rabbits were found to have no fleas at all, but apparent-
ly such a condition is temporary.

Table 3._Number of specimens of the common eastern rabbit flea, Cediopsylla simplex, taken from cottontails examined
in Lee County, Illinois, and average number per rabbit infested; also, number and per cent of rabbits infested.

Rabbits Fleas
Number | Number | Mean Per Cent Total Average Number Per
Month Year Examined Infested Infested Number Rabbit Infested,
With Fleas | WithFleas Taken 1952—1954
1952—1954

January 1952 - = =
1953 9 8 90 43 5
1954 1 1 8

February 1952 - _ =
1953 113 65 70 439 7.4
1954 40 39 330

March 1952 - - -
1953 ll ll 100 366 33.3
1954 — _ -

April 1952 ~ - =
1953 5 5) 100 123 24.6
1954 — = =

May 1952 4 4 13
1953 12 8 75 205 18.2
1954 — - =

June 1952 52 27 104
1953 9 4 54 24 6.0
1954 6 5 86

July 1952 13 5 15
1953 63 24 40 100 4.0
1954 4 3 15

August 1952 15 11 24
1953 8 1 57 1 2.0
1954 5 8

September 1952 77 40 150
1953 - - 5? _ 3.7
1954 _ - —

October 1952 74 37 181
1953 ie 39 56 142 4.6
1954 19 7 102

November 1952 7 31 105
1953 38 36 90 202 4.9
1954 26 25 147

December 1952 _ — a
1953 2 2 100 9 4.5
1954 = = =

TOTAL P 715 ax yee | 2,942

12

100

aa re) re.)
Oo ie) Oo

PER CENT OF COTTONTAILS INFESTED
nm
oO

PER CENT

\ AVERAGE NUMBER

ee ee Oo”
—
—<-

nm oO aS oO
Oo e) Oo Oo

AVERAGE NUMBER PER INFESTED COTTONTAIL

fe)

_

Fig. 10.—Monthly distribution (per cent of rabbits infested and average number on infested rabbits) of Cediopsylla sim-
plex in Lee County, 1952-1954. The graph is based on 3-month sliding scale of data in table 3.

It is interesting to compare the apparent seasonal
fluctuations in populations of this flea with populations
of other species. Evans & Freeman (1950), in a survey
of small mammals occurring near Oxford, England,
found that: ‘‘For each species of host, the monthly
indices point clearly to a rise, not only in the number
of fleas per host, but also in the numbers of hosts in-
fested, during the spring, with a maximum reached in
the summer and a subsequent decline to a winter low.
Such seasonal variation has been observed repeatedly,
yet it is by no means clear how much this is due to a
real decline in the numbers of fleas present inthe breed-
ing environment (the nests and burrows of the hosts),
how much to a decrease in flea activity, or how much

to changes in the numbers or activity of the host popu-
et al. (1951) reported

marked seasonal fluctuations in two species of fleas in

lation.’” Recently, Holdenried
California which have the same mammalian host. They
found that the peak of abundance for one flea was in
summer and the peak for the other was in winter.

Whatever may be the reason for the apparent abrupt
increase in numbers of the common eastern rabbit flea
on rabbits in Lee County in spring, the time of increase
coincides, perhaps significantly, with the main breeding
season of rabbits. Presumably, more occupied rabbit
nests are present in spring than at any other time of
year, a condition which is favorable for the development
of a maximum number of larval fleas.

13

Because this rabbit flea has been previously re-
corded in print from only one Illinois locality (Kohls
1940), additional records are marked on the accompany-
ing map, fig. 1], to demonstrate its state-wide occur-
rence on rabbits.

Spangler a
. ° ! i
eye atin tI A
\e ote ye
J B |
f\ | @ t
ee ee
ae be i !
Ke Spe 2 es ina
q eel ay hiiccaccael
‘alisha ! "ial ij
Po Aitp alece. et =; =4 e
ot eee bei | .
g I | Pe t ] ise =f
B | 9 De | t——
[eee ey [Fees
f ma! /
ee poe eap ek esi!
t ee ee eet Nea
ee ee fae j aa a ot
> ty j@ @.

Fig. 11.—Cediopsylla simplex distribution in Illinois,
based on Illinois Natural History Survey records.

Odontopsyllus multispinosus (Baker); giant eastern
rabbit flea; fig. 12. - The giant eastern rabbit flea is
primarily an ectoparasite of cottontails. Here in Illinois
and seemingly elsewhere, this insect is usually less
numerous on rabbits than the smaller-sized common
eastern rabbit flea. Nowhere throughout its range, from
the east coast to about the 100th meridian, has the
giant rabbit flea been found to be common. Shaftesbury
(1934), in speaking of the North Carolina fauna, stated,
“this latter species [O. multispinosus ] might be rela-
tively more abundant on some other kind of rabbit in
some other locality.’? So far, no one has discovered
this other kind of rabbit or this other locality. Rather,
this flea appears to be the minor rabbit flea of eastern
North America and may be scarce to rare on its rabbit
host fn all regions.

In Lee County, this flea was observed only on the
backs of rabbits, and most of the specimens were from
the lower backs. Apparently the two rabbit fleas divide
their rabbit host into territories; that is, the common
eastern rabbit flea occupies the front region, head and

ears, whereas the giant eastern rabbit flea occupies
the hind region.

14

The giant eastern rabbit flea was taken in Lee
County during every season of the year. Ninety-six adult
specimens were obtained from ]2 rabbits. Inasmuch as
more than 700 rabbits were examined, the 12 rabbits
infested by this flea represent less than 2 per cent of
the population studied. To our knowledge, and as
measured by relative abundance, this flea is of little
consequence as a rabbit ectoparasite, except perhaps
on rare occasions. Once, in late February, 1953, we
found a rabbit harboring 74 specimens. Usually each
infested rabbit had only one, two, or three individuals
of this flea.

In the collection of the Illinois Natural History
Survey, specimens have been preserved from rabbits at
Carbondale, Charleston, Cobden, Elkville, Starved Rock
State Park, Urbana, and Vandalia, as well as in Lee
County. The records given herein, fig. 13, constitute
the first published records for Illinois.

Opisocrostis bruneri (Baker). — Single specimens
of this ground squirrel flea were taken from rabbits in
Lee County on September 22, 1952, and on July 24,
October 8, October 11, November 3, and November 8,
1953. This flea was once found on a cottontail in cen-
tral Illinois in early April (INHS collection).

Ctenophthalmus pseudagyrtes (Baker). — Although
this flea is usually found on moles (Fox 1940), it in-
fests many other small mammals, including cottontails.
We collected this flea twice from cottontails in lee
County, once on January 2, 1954, and again on October
26, 1954.

Orchopeas howardii (Baker). — Ordinarily, this flea
occurs on tree squirrels. We have two records of it from
rabbits, one from Lee County on February 14, 1953, and
the other from central Illinois on May 5, 1948.

Epitedia wenmanni (Rothschild). — This mouse
flea was taken in Lee County from a cottontail on
November 9, 1954.

BOT FLIES

Cuterebra spp.; bot fly; fig. 14. — Bot fly larvae
were occasionally noticed in open ruptures of the skin
of rabbits, particularly in midsummer. In Lee County
all but 1 of our 11 records of bot fly larvae were taken
from rabbits in July; the exception, a large larva, was
found on November 5, 1952. In summer both medium-
sized and large larvae were found, even on the same
day and on the same host.

Cuterebra buccata (Fabricius). — Six of the bot fly
larvae collected from rabbits in Lee County were pro-
visionally determined as Cuterebra buccata by Dr. C.
Sabrosky of the United States National Museum. One
larva, of large size, collected from a rabbit in Lee
County on July 9, 1953, pupated in soil provided for it

Fig. 12.—Odontopsyllus multispinosus, giant eastern rabbit flea, adult female. The absence of toothlike spines below
the eyes and the presence of two rows of setae (instead of one row) on each abdominal tergite are features that distinguish

this species from Cediopsylla simplex.

and emerged as an adult 2 months later, September 7.
The reared adult was determined positively as buccata.
Cuterebra cuniculi (Clark) and Cuterebra horripilum
Clark. — In the collection of the Illinois Natural His-
tory Survey, there are six other specimens of bot flies;
they were taken from Illinois rabbits in summer, 1883-
1917. Some of these larvae are much larger in size
than those found in Lee County and are presumably not
Cuterebra buccata. Those that were reared to the adult
stage were determined by the late C. T. Greene as
cuniculi, a characteristically larger fly than buccata.
According to our records, the pupa of cuniculi, unlike
the pupa ofbuccata, spends about 10 months in the soil,
One larva taken in Urbana on July 22, 1890, emerged as
an adult on May 22, 1891. Another larva collected from
the same locality on August 4, 1890, emerged May 19,
1891. Several of the specimens of cuniculi from central
Illinois were from the neck region of cottontails.

One of the large unidentified bot fly larvae taken
in Lee County may be cuniculi or the closely allied
species, horripilum, rather than buccata.

CHIGGERS

Euschongastia peromysci (Ewing); Trombicula
(Eutrombicula) alfreddugesi (Oudemans); Trombicula
(Neotrombicula) whartoni (Ewing). — Chiggers infest a
wide variety of mammal and bird hosts. On rabbits they
are most commonly attached to the inside of the ears.
[hey occur frequently on cottontails in central and
southern [llinois, but apparently rarely in the northern
part of the state. Where found in [llinois, Trombicula
(Neotrombicula)

whartoni late

autumn and winter, Euschéngastia peromysci in late

infests cottontails in

winter, and Trombicula (Eutrombicula) alfreddugesi in

late spring and summer.

f e =
Aa
f : lier :
{ L .
y -_-- — eee '
t-| ae) -—-—-—
/ | eeu
f ees (= pee l| j
cas is Ff t - ‘
Cs; | i = 1 feral
pee a Me)
[- = f Py proces | i
> mae’ = 1
eat ae ail Lal | ~
5 Soe! J
T {| —+4—-—~
j i JS |
5 a = acer (a j
T (Ni @ fH
ae 7 Seat cola
\ | Png lie he
\ |e, e e \ L
fs | DE
Ie Nell ih ne hp
Sp 2) l | f
| es
f Le +-.--4 et
re ae ieee
xe fer ee
PY Oo eis
gy C= amias
ee ti ee

Fig. 13.—Odontopsyllus multispinosus distribution in IIli-
nois, based on []linois Natural History Survey records.

No chiggers were taken on rabbits in Lee County;
possibly they were overlooked.

CONCLUSIONS

Ectoparasites of cottontail rabbits, particularly the
continental rabbit tick, Haemaphysalis leporis-palustris,
are significant components of the wildlife of Illinois,
and, as such, have had a decided effect on man’s activ-
ities inrecent years. Because of newly gained knowledge
of the seasonal behavior of the continental rabbit tick
on cottontails, the Illinois hunting laws were changed
in 1955. Ecke (1948) and Yeatter & Thompson (1952)
had shown conclusively, as we found during our studies
in Lee County, 1952-1954, that those ticks which are
vectors of tularemia are absent from rabbits in late fall
and most of the winter in northern and central Illinois.
Postponement of the hunting season until late fall to
avoid the tick season and the consequent hazards of
tularemia was the logical course of action which fol-
lowed the reports of such information.

In our limited survey of ectoparasites of cotton-
tails in Lee County, we observed the following funda-
mental features of the intricate relationships between
ectoparasite and host: (1) Adults of the continental
rabbit tick rarely feed on rabbits in fall. (2) Ticks and
fleas reach their greatest abundance at different sea-
sons of the year, as if each of the two groups gains an

16

advantage by a division of time on the host. (3) The
eastern rabbit flea, Cediopsylla simplex, occupies the
head region of its host, whereas the giant eastern rabbit
flea, Odontopsyllus multispinosus, occupies the back of
its host, as if each of the species gains an advantage
by eliminating competition for space. (4) The variable
wood tick, Dermacentor variabilis, as an adult, is ab-
sent from rabbits when, in the same geographical region,
it heavily infests other mammals such as opossums
and raccoons. (5) Only two species of ectoparasites,
the continental rabbit tick and the common eastern rab-
bit flea, are consistently numerous at certain seasons,
whereas other ectoparasites, such as Odontopsyllus
multispinosus and Ixodes dentatus, which are supposedly
equally restricted and equally adjusted to rabbit hosts,
remain relatively rare most of the time.

Asis indicated bythe aforementioned observations,
the behavior patterns of ectoparasites of rabbits are
extremely complicated. What factors, it may be asked,
could catise one of the two ticks and one of the two
fleas restricted to rabbits to be common and the others
to be rare? Or what factors could cause the adult of the
variable wood tick to infest almost every mammal the
size of a rabbit or larger, but not be found on rabbits?
Why do the ticks that are primarily ectoparasites of
rabbits feed in the adult stage only on rabbits, yet in
the immature stages find birds as acceptable as rabbits?

Surveys such as ours cannot provide answers to
many questions; rather, they provide a few facts that
suggest further questions. Thorough and detailed in-
vestigations of the life history and environment of each
ectoparasite and the habits and environment of the host
need to be undertaken and correlated before much can
be deduced as to the origins and the conditions for
optimal survival of ectoparasites.

Ectoparasites of cottontail rabbits, because they
are easy to obtain and because preliminary studies on
them have been made here and elsewhere, are worth-
while subjects for future research.

SUMMARY

Seven facultative or obligate ectoparasites were
taken from about 700 cottontail rabbits collected in Lee
County, northern Illinois, in a period beginning in May,
1952, and ending in November, 1954.

The continental rabbit tick, Haemaphysalis leporis-
palustris, the principal vector of tularemia, was the
most common tick found. Very few specimens were col-
lected from rabbits from late autumn to late winter.

Adults of this tick were collected from rabbits
from late winter to midsummer. They reached their great-
est abundance on cottontails in spring. The adults rare-
ly infested rabbits in autumn or early winter; they were

Fig. 14.—Cuterebra sp., bot fly larva, dorsolateral view. Actual size about 1-1/4 inches.

present, however, in leaf mold, even before cold weather
set in.

Larvae of this tick apparently suffered high losses
during winter, and few were found in spring. In mid-
summer, larvae of the new generation hatched and then
reached the peak of their abundance on rabbits in Au-
gust and September.

Nymphs of the new generation reached their peak
of abundance on rabbits in September and Qctober. Un-
like larvae, nymphs commonly survived the winter and
reappeared fairly abundantly on rabbits in early spring.

The proportion of rabbits infested with the conti-
nental rabbit tick, in any stage, varied with the season.
Ninety per cent of the rabbits examined harbored this
tick in August and September, 0 per cent in midwinter,
75 per cent in spring, and 50 per cent in early summer.

The variable wood tick, Dermacentor variabilis, the
principal vector in Illinois of Rocky Mountain spotted
fever, was found principally in spring, and even then
not commonly. Possibly because of the behavior pat-
terns of this tick and the rabbit, only larvae and nymphs
were found feeding on cottontails in Lee County.

The eastern rabbit tick, [xodes dentatus, although
almost exclusively restricted to rabbits, was found to
he rare on cottontails in Lee County.

The common eastern rabbit flea, Cediopsylla sim-
plex, was the flea most often collected. It was found
primarily around the head and neck region of rabbits.
This flea infested cottontails throughout the year; it
was most abundant in early spring and least abundant
in late summer. It was observed to have a sex ratio of
about 2 females to 1 male. The largest number of fleas
of this species found on one rabbit was 101; the aver-
age per rabbit examined was approximately 4. On a few
rabbits no fleas were found.

The giant eastern rabbit flea, Odontopsyllus multi-
spinosus, which seemed to prefer to feed on the hind
regions of cottontails, was taken occasionally at all
seasons. It was not found to be abundant except in
rare instances.

Fleas of four additional species normally found on
other mammals were taken several times on cottontails
in the Lee County study area. These specimens had
probably strayed to rabbits accidentally.

Cuterebra buccata was the principal bot fly ob-
tained from cottontails in Lee County. Larvae were
found, mostly during the summer, in open ruptures of
the skin of rabbits. One of the large unidentified larvae
may prove to be cuniculi or horripilum.

No chiggers were found on the rabbits examined.

LITERATURE CITED

Bell, J. F., and W. S. Chalgren
1943. Some wildlife diseases in the eastern United States. Jour. Wildlife Mgt. 7(3):270-8.
Bishopp, F. C., and Helen Louise Trembley
1945. Distribution and hosts of certain North American ticks. Jour. Parasitol. 31(1): 1-54.
Burbutis, Paul P., and Robert E. Mangold
1956. A study of the fleas of cottontail rabbits in New Jersey. Jour. Wildlife Mgt. 20(2):217-8.
Cooley, R. A.
1932. The Rocky Mountain wood tick. Mont, Ag. Exp. Sta. Bul. 268. 58 pp.
Cooley, R. A., and Glen M. Kohls
1945. The genus Ixodes in North America, Natl, Inst. Health Bul. 184. 246 pp.
Ecke, Dean Hobart
1948. The cottontail rabbit in central Illinois. Master’s thesis, University of Illinois, Urbana. 136 pp.
Ecke, Dean H., and Ralph E. Yeatter
1956. Notes on the parasites of cottontail rabbits in Illinois. I]. Acad. Sci. Trans., 1955, 48: 208-14.
Eddy, Gaines W.
1942. Notes on the seasonal history of the rabbit tick, Haemaphysalis leporis-palustris, in Oklahoma. Ent. Soc. Wash.
Proc. 44(7): 145-9.
Eddy, Gaines W., and C. R. Joyce
1944. The seasonal history and hosts of the American dog tick, Dermacentor variabilis, in lowa. lowa State Col. Jour.
Sci. 18(3):313-24,
Evans, F. C., and R. B. Freeman
1950. On the relationships of some mammal fleas to their hosts. Ent. Soc, Am, Ann, 43(3):320-33.
Ewing, Henry E., and Irving Fox
1943. The fleas of North America. U. S. Dept. Ag. Misc. Pub. 500. 142 pp.
Fox, Irving
1940. Fleas of eastern United States. Iowa State College Press, Ames, Iowa. 191 pp.
Green, Robert G.
1939, Tularemia a common disease in wild animals. Minn. Cons. 67: 14-6,
Green, R. G., C. A. Evans, and C. L. Larson
1943, A ten-year population study of the rabbit tick, Haemaphysalis leporis-palustris. Am. Jour. Hyg. 38(3): 260-81.
Holdenried, R., F. C, Evans, and D. S, Longanecker
1951. Host-parasite-disease relationships in a mammalian community in the central coast range of California. Ecol.
Monog,. 21(1):1-18.
Hooker, W. A., F, C. Bishopp, and H. P. Wood
1912, The life history and bionomics of some North American ticks. U. S. Dept. Ag. Bur. Ent. Bul. 106. 239 pp.
Joyce, C. R., and Gaines W. Eddy
1943, Host and seasonal notes on the rabbit tick, Haemaphysalis leporis-palustris. lowa State Col. Jour. Sci. 17(2):20512.
Kohls, Glen M.
1940. Siphonaptera: a study of the species infesting wild hares and rabbits of North America north of Mexico. Natl. Inst.
Health Bul. 175. 34 pp.
Philip, Cornelius B.
1939, Tularaemia in Alaska, Pacific Sci. Cong. (6th) Proc. 5:71-3.
Portman, Roland W.
1944, Winter distribution of two ectoparasites of the cottontail rabbit in Missouri. Jour. Econ, Ent. 37(4):541.
Price, Winston H.
1954, The epidemiology of Rocky Mountain spotted fever. II. Studies on the biological survival mechanism of Rickettsia
rickettsii. Am. Jour. Hyg. 60(3):292-319.
Shaftesbury, Archie D,
1934, The Siphonaptera (fleas) of North Carolina, with special reference to sex ratios. Elisha Mitchell Sci. Soc. Jour.
49( 2): 247-63.
Smith, Carroll N,
1945. Biology of Ixodes dentatus Neumann (Ixodidae). Ent. Soc. Am. Ann. 38(2):223-33.
Smith, Carroll N., Moses M. Cole, and Harry K. Gouck
1946, Biology and control of the American dog tick. U. S. Dept. Ag. Tech. Bul. 905. 74 pp.
Stone, Witmer, and William Everitt Cram
1902, American animals. A popular guide to the mammals of North America north of Mexico, with intimate biographies of
the more familiar species. Doubleday, Page & Co., New York. 318 pp.
Yeatter, Ralph E., and David H. Thompson
1952. Tularemia, weather, and rabbit populations, Ill. Nat. Hist. Surv. Bul. 25(6):35 1-82.

Some Recent Publications of the
ILLINOIS NATURAL HISTORY SURVEY

BULLETIN

Volume 26, Article 1._The Mayflies, or Ephemeroptera, of
Illinois. By B. D. Burks. May, 1953. 216 pp., frontis., 395
figs., bibliog. $1.25.

Volume 26, Article 2.—Largemouth Bass in Ridge Lake, Coles
County, Illinois. By George W. Bennett. November, 1954.
60 pp., frontis., 15 figs., bibliog.

Volume 26, Article 3.—Natural Avail ability of Oak Wilt Inocula.
By E. A. Curl. June, 1955. 48 pp., frontis., 22 figs., bibliog.

Volume 26, Article 4.—Efficiency and Selectivity of Commer-
cial Fishing Devices Used on the Mississippi River. By
William C. Starrett and Paul G. Barnickol. July, 1953. 42 pp.,
frontis., 17 figs., bibliog.

Volume 26, Article 5.—Hill Prairies of Illinois. By Robert A.
Evers. August, 1955. 80 pp., frontis., 28 figs., bibliog.

Volume 26, Article 6.~Fusarium Disease of Gladiolus: Its
Causal Agent. By Junius L. Forsberg. September, 1955.
57 pp., frontis., 22 figs., bibliog.

Volume 27, Article 1.—Ecological Life History of the War-
mouth. By R. Weldon Larimore. August, 1957. 84 pp., color
frontis., 27 figs., bibliog.

CIRCULAR

39.—How to Collect and Preserve Insects. By H. H. Ross.
June, 1953. (Fourth printing, with alterations.) 59 pp., frontis.,
65 figs.

42.—Bird Dogs in Sport and Conservation. By Ralph E. Yeat-

_ ter. December, 1948. 64 pp., frontis., 40 figs.

45.—Housing for Wood Ducks. By Frank C. Bellrose. Febru-
ary, 1955. (Second printing, with revisions.) 47 pp., illus.

46.—Illinois Trees: Their Diseases. By J. Cedric Carter. Au-
gust, 1955. 99 pp., frontis., 93 figs. Single copies free to
Illinois residents; 25 cents to others.

47.—Illinois Trees: Their Insect Enemies. By L. L. English.
May, 1958. 92 pp., frontis., 59 figs., index. Single copies
free to Illinois residents; 25 cents to others.

BIOLOGICAL NOTES

28.-Home Pools and Homing Behavior of Smallmouth Black
Bass in Jordan Creek. By R. Weldon Larimore. June, 1952.
12 pp., 5 figs., bibliog.

29.~An Inventory of the Fishes of Jordan Creek, Vermilion
County, Illinois. By R. Weldon Larimore, Quentin H. Pick-
ering, and Leonard Durham. August, 1952. 26 pp., 25 figs.,
bibliog.

30. —Sport Fishing at Lake Chautauqua, near Havana, Illinois,
in 1950 and 1951. By William C. Starrett and Perl L. McNeil,
Jr. August, 1952. 31 pp., 22 figs., bibliog.

31.—Some Conservation Problems ofthe Great Lakes. By Har-
low B. Mills. October, 1953. (Second printing.) 14 pp., illus.,
bibliog.

32.—Some Facts About Illinois Snakes and Their Control. By
Philip W. Smith. November, 1953. 8 pp., 11 figs. 10 cents.

33.—A New Technique in Control of the House Fly. By Willis
N. Bruce. December, 1953. 8 pp., 5 figs.

34.—White-Tailed Deer Populations in Illinois. By Lysle R.
Pietsch. June, 1954. 24 pp., 17 figs., bibliog.

35.—An Evaluation of the Red Fox. By Thomas G. Scott.
July, 1955. (Second printing.) 16 pp., illus., bibliog.

36.— A Spectacular Waterfowl Migration Through Central North
America. By Frank C. Bellrose. April, 1957. 24 pp., 9 figs.,
bibliog.

37.—Continuous Mass Rearing of the European Corn Borer in
the Laboratory. By Paul Surany. May, 1957. 12 pp., 7 figs.,
bibliog.

MANUAL

3.—Fieldbook of Native Illinois Shrubs. By Leo R. Tehon.
December, 1942. 307 pp., 4 color pls., 72 figs., glossary,
index. $1.75.

4.—Fieldbook of Illinois Mammals. By Donald F. Hoffmeister
and Carl O. Mohr. June, 1957. 233 pp., color frontis., 119
figs., glossary, bibliog., index. $1.75.

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45d

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