One-week-old Warble of the
Tree Squirrel Bot Fly

During the first week, a reddened lump (the warble) starts to form in the squirrel's hide, and the translucent, pale white posterior tip of the larva begins to protrude from the warble pore (image at right). Discharge from the warble pore (probably a combination of host tissue exudate and larval excretion) tends to be a clear to slightly yellowish fluid.




By the end of the first week after the larva cut the warble pore, the warble has become a moderately sized lump in the squirrel's skin (image at left).

In a closeup view of the warble (below), the posterior tip of the larva is protruding naturally from the warble pore, and discharge mats the squirrel's fur. It is unclear whether this material is exclusively larval excrement or also includes fluid discharged from the host's wound, but some of this residue appears to be host blood, probably resulting from damage to the host's tissues as the larva expands the warble and establishes its feeding site. However, the larva presumably does not generally feed on the host animal's blood (such as fleas and mosquitoes do) but rather on other body fluids ('tissue exudate').








  • Tree Squirrel Bot Fly (home page)
         Frank Slansky & Lou Rea Kenyon // fslansky@ufl.edu
         Version 1.1 (updated July 26, 2001)