Warbles

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What causes 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 larvae hatch, 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.

Warble fly larvae under caribou skin.

Where do warbles occur?

In the NWT and Nunavut, warble fly larvae are very common in caribou and reindeer.

What are the signs of warbles?

Caribou usually appear healthy, although animals with heavy infections may be weak.

While laying their eggs, warble flies can 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 2.5 cms long.

There is often swelling and fluid in nearby tissue.

The number of warbles can range from 1 to over 100 on each animal.

How can I protect myself?

You cannot be infected by warble flies or their larvae.

Can I eat the meat?

Meat from affected animals is suitable for human consumption.

Warbles in caribou reduce the quality of both hide and carcass.

Samples to collect

Larvae of the warble fly.

Photo credit: P. Nicklen