NAME: Blacklegged/deer/bear tick
SCIENTIFIC NAME: Ixodes scapularis Say
common name blacklegged refers to their dark legs which are in contrast
to the paler body and that of deer because the preferred adult host
is the white-tailed deer; in the midwest, it is called the bear
tick. This tick is of medical importance because it is an important
vector of Lyme disease. Blacklegged ticks are found primarily in
the northeastern, midwestern, and southeastern states in the United
States, but extend into Mexico. In error, this tick was described
in 1979 as the new species Ixodes dammini by Spielman, Clifford,
Plesman & Corwin; this error was corrected by Olivier, Jr.,
et. al. in 1993.
female about 118" (2.7 mm) long, male smaller (about 1/16"12
mm). Body oval, dorsoventrally flattened (top to bottom), not hard-shelled.
Color orangish brown except legs, mouthparts and scutum (dorsal
shield just behind mouthparts) dark reddish brown but abdomen darker
when engorged; male body reddish brown overall. Scutum present,
longer than wide, almost completely covering dorsum in male. Eyes
lacking. Capitulum (mouthparts and their base) visible from above;
hypostome (toothed median mouthpart) with apex sharply pointed.
Coxa I (1st pair of legs) with internal spur (projection from coxal
base) overlapping coxa II (2nd pair of legs). Abdomen with anal
groove in front of anus; lacking abdominal festoons (rectangular
areas divided by grooves along posterior margin).
1st instar larvae about 1/32" (0.7-0.8 mm) long, with 6 legs;
2nd instar nymphs about 1/16" (1.1-1.8 mm) long, with 8 legs.
Pacific/western blacklegged tick (Ixodes pacificus) with scutum
(dorsal shield) almost round (subcircular); (2) Other ixoda ticks
(non-Ixodes) with anal groove either behind anus, indistinct, or
absent, festoons often present; (3) Soft ticks (Argasidae) lack
a scutum (dorsal shield), with capitulum (mouthparts and their base)
ventral, not visible from above.
the life cycle (egg to egg) can be completed in 2 years in nature,
it may be extended to 4 years it hosts are scarce. Adult ticks feed
during the winter primarily on the white-tailed deer, Odocoileus
virginianus (Zimmermann). Here they mate, with the male dying shortly
after mating and the female remaining on the host. In the spring,
the female drops off the host and deposits about 3,000 eggs. The
6-legged larvae hatch out in several weeks (48-135 days) and can
be found June through September. They feed for 3-9 days but only
once, usually on small mammals such as mice, chipmunks, voles, etc.
but the preferred larval host is the white-footed mouse, Peromyscus
leucopus Rafinesque. Larvae feeding before September molt promptly
and overwinter as 8-legged nymphs; those which feed later, overwinter
engorged and molt into nymphs the following spring. Nymphs feed
for 3-8 days but only once during the summer, usually on mice or
larger mammals such as squirrels, raccoons, opossums, skunks, dogs,
and humans, or on birds. Nymphs can be found from April through
August, with the population usually peaking in June or July. These
fed nymphs then require 25-56 days to molt into adults in the autumn.
The adults attach primarily to the white-tailed deer, engorge, and
mate. The male dies after mating but the female continues to feed
until egg development is completed and remains on the deer until
spring when she drops off to lay eggs. Shortly after her eggs are
laid, the female dies.
adults do not feed during their first season (autumn through spring),
they die before summer's end. If nymphs do not feed their first
season (summer), most die off but they can survive through 2 seasons
(May through August of the next year); they develop into adults
in the same year in which they feed. Unfed larvae survive less than
one year, they usually survive the winter but die during the following
disease is caused by the spirochete, Borrelia burgdofferi Johnson,
Schmid, Hyde, Steigerwalt & Brenner, which is a corkscrew-shaped
bacteria. Its primary wild reservoir is the white-footed mouse which
is infected by the spring-feeding, pathogen-infected blacklegged/deer
tick nymphs. These white-footed mice then serve to infest the later-feeding
blacklegged/deer tick larvae, which keeps the disease cycle going.
Tick eggs don't contain the spirochete, so it is acquired via feeding.
is the pathogen-infected blacklegged/deer tick nymphs, which are
most active in mid-summer (May-July) and use a wide variety of hosts,
that are primarily responsible for Lyme disease in humans in the
northeast and midwest. Larvae and nymphs have been collected on
29 species of mammals in 7 orders, and from 49 species of birds
(23 species being migratory birds) in 17 different families.
the west, the primary Lyme disease vector is the Pacific/western
blacklegged tick, Ixodes pacificus Cooley and Kohls, while in the
south the vector(s) is suspected to be the lone star tick, Amblyomma
ticks climb grass and shrubs to wait for a passing host, and move
very little laterally. They concentrate on such vegetation located
in transitional areas/zones such as where forest meets field, mowed
lawn meets unmowed fence line, a foot/animal trail through high
grass or forest, etc.Because
these transitional areas or edge habitats are where most animals
travel sometime each 24-hour period, this is where the ticks are
mostly likely to acquire a host.
other habitat most likely to harbor ticks is the den, nest, or nesting
area of its host such as that of skunks, raccoons, opossums, but
especially the white-footed mouse. The white-footed mouse prefers
woody or brushy areas. It nests in any place that gives shelter
such as below ground, in stumps, logs, old bird or squirrel nests,
woodpiles, buildings, etc.
feeding area for these ticks on humans is at the back of the neck,
at the base of the skull; long hair makes detection more difficult.
However, the ticks will usually wonder about for up to 4 hours or
so before they attach. Then, a tick has to be attached for a period
of 6-8 hours before a successful transmission can take place.
reduction of these ticks is a 6-step process. The first 2 are sanitation
and personal protection, which are the responsibility of the homeowner
or occupant(s) but usually require education by the PCO.
Sanitation, consists of the following: (a) keep grass cut low including
around fence lines, sheds, trees, shrubs, swing sets and other difficult
to cut locations; (b) remove weeds, woodpiles, and other debris
which are attractive to mice as nesting areas, and leaf litter which
is attractive to ticks, especially the nymphs; (c) keep garbage
can lids on tightly to discourage opossums, raccoons, and skunks
from coming into the yard to raid garbage cans for food because
these animals all harbor the ticks which transmit the Lyme disease
pathogen; (d) discourage feeding birds because the seeds attract
deer mice, the major reservoir host for the Lyme disease pathogen;
and (e) install a chimney screen to keep squirrels, raccoons, and
Personal protection, consists of: (a) use deet or permethrin containing
repellent and tuck pants into socks or boots when going into suspect
areas; (b) check children for ticks when they come into the house
because it takes up to 4 hours, possibly longer, for the tick to
start feeding; (c) wear light colored clothing which makes spotting
ticks easier; (d) pets which go outdoors may increase the chance
of the occupant's encounter with these ticks, especially cats; and
(e) encourage the vet to check any pet's blood to determine if they
are carrying the Lyme disease spirochete.
Inspection, is done by performing a tick drag on a routine basis
in areas where the ticks have been reported or for homes adjacent
to heavily wooded or uninhabited areas. The drag consists of light
colored heavy duty cloth, 7 feet long by 2 feet wide, which is securely
weighted at both ends. A rope is attached to one end and this drag
is walked around the suspect property.
Treat the perimeter of the property or the entire property with
an appropriately labeled pesticide if ticks show up on the drag.
Wettable powder and microencapsulated formulations work best.
Do an exterior perimeter rodent control program using PVC pipe with
a glue board placed inside.
Use the product which has cotton balls treated with a residual pyrethroid
placed inside open cylinders as per label directions. The cotton
is harvested by mice as a nesting material and when ticks come in
contact with it, they die.
symptoms are usually divided into 3 stages, and they mimic several
different commonly occurring diseases.
Spreading rash, fever, flu-like symptoms, aches.
Stage 1: Expanding rash (Erythema migrans or EM rashes). 3-30 days
appearance to rash.
o One or more rash sites.
o May or may not have flu symptoms.
o May come and go or persist.
Stage 2: Complications or disorders of the heart or nervous system.
Varying degrees of blockage of the heart muscle.
Nervous system. Meningitis, encephalitis, facial paralysis.
o "Bell's palsy," other conditions involving peripheral
o Migratory pain in joints, tendons, muscles, and bones, often without
joint swelling or redness.
Stage 3: Months to years after disease onset.
Arthritis that appears and disappears intermittently for several
o Enlarged knee joints.
o Erosion of cartilage and bone.
Once bitten by a blacklegged/deer tick possessing the spirochete,
it may not produce antibodies in the victim for up to 6 weeks. Therefore,
it takes time to verify that one has Lyme disease.
Oral medications for Lyme disease can destroy the spirochetes in
the blood and give an antibody reading that the person is "cured."
However, the spirochete may persist in the brain and reappear in
the person 5-10 years later. Therefore, intravenous treatment is
advised over oral medications by some physicians considered experts
in this area, especially for persons showing Stage 2 and Stage 3
The best way to remove a tick found attached to a person or pet
is to firmly grasp it with a pair of tweezers as close to the skin
Pull firmly but gently backwards until the tick pulls free.
Do not touch the tick, but save it in rubbing alcohol for later
Epidemiologists have isolated an unidentified type of spirochete
from ticks collected in southeastern Missouri which appears to be
different from Borrelia burydofferi.
Initial studies show that infection by this "new/different"
spirochete can result in the expanding rash (EM) but that it is
less often followed by multiple skin lesions than with Lyme disease.
Therefore, more than one species of tick may be the vector. It is
best to characterize the Missouri victims as suffering from a "Lyme-like"
illness rather than Lyme disease.
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