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Fuzzy Wonders: Woolly Bears

Even though many of us may be returning to school, that doesn’t mean it’s time to stop exploring the outdoors. It’s around this time of year that one of the coolest and cutest critters starts to crawl around: woolly bear caterpillars!

Seeing a woolly bear is considered to be a sign of the changing seasons from summer to fall for many people across North America. The woolly bear’s range stretches from the northern parts of Mexico, throughout the United States and into southern Canada.

You have probably seen these fuzzy caterpillars before, maybe on a walk to school, around the park, or even in your own backyard. Although easily recognized, most people don’t know what to call them, and sadly don’t know all the exciting traits they have. Let’s dive into some questions you never knew you needed to ask until now.

If woolly bears are caterpillars… what butterfly do they turn into?

Woolly bears do not turn into butterflies! They actually turn into the Isabella tiger moth. These moths have a 2 inch wingspan and are a light yellow colour with black spots.

It’s almost winter and there are still caterpillars crawling around! When are they going to become moths?

A woolly bear will not turn into a moth until next spring or early summer. The caterpillar will keep munching on leaves until winter begins. 

If they wait until spring to become moths, how do they survive the long, cold winter?

A woolly bear, unlike most caterpillars, will remain a caterpillar all winter, unlike other species that overwinter as a pupa (in a cocoon). The woolly bear will roam the forest floor, across trails and roads to find a good dark spot under leaf litter or under logs to spend the winter. When the temperatures get below freezing, this caterpillar produce a chemical in their body that acts like an antifreeze. This makes sure their blood doesn’t form ice crystals. Wow!

Is it safe for me to pick up a woolly bear?

YES! There are some species of caterpillars you should not touch (because their “hairs” or spines can irritate your skin), but woolly bear caterpillars are safe to touch. This fuzzy caterpillar is exactly that … FUZZY. It’s hairs are probably there to trick predators into thinking they are toxic so they don’t become a meal. So next time you’re outside and find a woolly bear caterpillar, you can gently pick it up, pet it, and see for yourself how fuzzy they are!

Is it true that the length of the brown band predicts the kind of winter we’ll have?

This is a common belief: the length of the brown and black bands on the woolly bear caterpillar tells us if we will have a cold snowy winter or not. The legend goes, if the brown band in the middle is short, we will have a cold, snowy winter. On the other hand, if the brown band is long we will have a mild winter. It turns out that these caterpillars don’t actually tell us about the weather. The length of the bands depends on the caterpillar’s age and how much it was able to eat. If the middle brown band looks short, it means that the “ends” of the caterpillar (the black parts) have been growing a lot. Probably that caterpillar ate a lot and was able to grow quite long. 

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