From my local paper:

From Panama City, FL (AP)
-- Squirrelly behavior is common this time of year, state conservation
officials say.
The sight of a squirrel with lumps all over it's body, jumping in
the air, rolling on the ground and generally acting nutty is no cause
for alarm, Lt. Stan Kirkland of the Florida Fish and Wildlife
Conservation Commission said Wednesday.
"When People call they describe these unusual antics, as well as
large lumps on the squirrel's body that appear to be cancerous
tumors," Kirkland said. "In fact, they are cause by warbles, which
are bot fly larvae growing just under the squirrel's skin."
Once the larvae emerge, the squirrel generally recovers without
further incident, but the insects can be a real annoyance while
burrowed.
In the Southeast, gray squirrels, rabbits, and other rodents are
commonly affected by bot fly warbles, Kirkland said. Horses and
cattle also sometimes get them.
Neither the larvae nor the affected animals are a threat to humans
or pets, Kirkland said.


Shelly