#83 Isabella Tiger Moth caterpillar

Isabella Tiger Moth caterpillar (Pyrrharctica isabella)

21 May

Caterpillar commonly known as the “woolly bear”. The thirteen-segment larvae are usually covered with brown hair in their mid-regions and black hair in their anterior and posterior areas. In direct sunlight, the brown hair looks bright reddish brown. Adults are generally dull yellowish through orangish and have robust, scaly thorices; small heads; and bright reddish-orange forelegs. Wings have sparse black spotting.

The isabella tiger moth can be found in many cold regions, including the Arctic. The banded woolly bear larva emerges from the egg in the fall and overwinters in its caterpillar form, when it literally freezes solid. First its heart stops beating, then its gut freezes, then its blood, followed by the rest of the body. It survives being frozen by producing a cryoprotectant in its tissues. In the spring it thaws.

Larval setae do not inject venom and are not urticant; they do not typically cause irritation, injury, inflammation, or swelling. Handling larvae is discouraged, however, because their sharp, spiny hairs may cause dermatitis in some people. When disturbed, larvae defend themselves by playing possum (rolling up into balls and remaining motionless) and quickly crawling away.

** Note: Executive decision – for the purposes of the 1000 species project larvae such as this caterpillar will be treated as separate species to the adults. So should I happen upon an adult of this then it will count as two “species” towards the 1000 target.

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