Meet the Botfly
Squirrels with Barnacles?
Click photo for larger image for downloading
Mrs. Stacy Wood's
two cats, Martha and Lula, watch squirrels covered with "barnacles."
By Sherry Kughn
JSU News Bureau
25 October 2004 Jacksonville State University employee
Stacy Wood opened the glass sliding door at her Talladega home one morning
so her cats Martha and Lula could watch the squirrels. She saw squirrels
covered with barnacle-like growths on their heads and backs frolicking
in her cedar bird feeder.
Mrs. Wood took pictures. Squirrel hunters in the area are probably familiar
with the phenomena that Mrs. Wood found out later was an infestation
of bot flies, or to be more accurate Cuterebra emasculator Fitch,
which, according to Dr. Cole Benton, JSU zoologist, look like “a stream-lined
The bot flies lay eggs throughout the summer. During late summer or
early fall, the eggs become larvae and crawl into the noses, ears, or
other orifices of squirrels, burrowing into the animal’s muscles and
emerging beneath the skin. The process creates a brown-colored lump
called a warble and is about the size of a penny. Then they eat a tiny
hole in the middle of
the lump to breath.
“They last a few weeks,” said Dr. Benton. “Then the larva
crawls out and pupates in ground litter.”
The bot fly pupa stays dormant for the winter and emerges as a fly in
Mrs. Wood was worried about her cats, “two spoiled-rotten pets who live
She worried unnecessarily, though, because the chance of her pets becoming
infected is rare. Pet owners whose animals live outdoors, though, and
even people who climb trees, such as children or tree cutters, have
been known to become infected with the larvae of the bot fly.
“These are accidental cases of myiasis, which is an infestation with
larvae,” said Dr. Benton. “Usually larvae are very selective of where
they lay their eggs and of whom they choose as hosts.”
If the larvae infect the wrong hosts, usually the larvae do not survive,
said Dr. Benton, and they rarely complete their life cycle in humans
or pets. Even for the unlucky squirrels or rabbits, the long term effect
is usually minimal, he said.
larvae exit, the skin shrinks and returns to normal. The animals that
get them, said Dr. Benton, might become sterile if the larvae get into
the scrotum. In the worst case scenario, a bacterial infection from
the larvae can spread throughout an animal whose immune system might
be weakened by the infestation. Death could result.
A website that tells all about bot flies is http://botfly.ifas.ufl.edu/abotfly/overview.htm,
which is sponsored by the University of Florida in Gainesville, Fla.
Its authors state that squirrels are probably uncomfortable while infected,
but transporting them to a veterinarian to surgically remove the warbles
would cause the animal more stress than allowing nature to take its
(University of Florida photos used with permission.)
Sherry Kughn can be reached at firstname.lastname@example.org.
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