A Field Guide
TO COMMON WILDLIFE DISEASES
AND PARASITES IN ALASKA

WARBLES

Underside of caribou hide with several warbles.

• Warbles are parasitic larvae of the warble fly.
• Lifecycle: The adult fly lays eggs on the hairs of the caribou’s legs and lower body. The eggs hatch into larvae. The larvae penetrate the skin, and travel under the skin to the caribou’s back. The warbles grow there until early summer, when they break through the skin and drop to the ground.

• Warbles can be found on caribou throughout their range in Alaska.

• Caribou usually appear healthy, although animals with heavy infections may be weak.
• While laying their eggs, warble flies harass caribou and interfere with feeding.
• Warble fly larvae are found under the skin on the caribou’s back.
• Larvae are yellowish-white, oval grubs about 1 inch long.
• There is often swelling and fluid in nearby tissue.
• The number of warbles can range from 1 to over 1000 on each animal.

• You cannot be infected by warble flies or their larvae.

• Meat from affected animals is suitable for human consumption.
• Warbles in caribou reduce the quality of both hide and carcass.

• Larvae of the warble fly

Warble fly larva.