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Can Woolly Bears Predict the Weather?

Updated: May 25

Woolly Bear Weather Prediction

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"No winter lasts forever; no spring skips its turn." ~ Hal Borland

The Isabella Moth Caterpillar

As winter is quickly approaching, we are seeing more Isabella tiger moth caterpillars. These insects are often referred to as the woolly bear, banded woolly bear, woolly worm and the black-ended bear.

According to folklore, the woolly bear caterpillar can predict the severity of the coming winter. The more black bands the critter has the harsher the winter conditions will be. So, if you love cold snowy winters, you want more black bands.

Isabella Tiger Moth Caterpillar Woolly Bear Caterpillar
Isabella Tiger Moth Caterpillar

How Does the Woolly Bear Predict the Weather?

The average woolly bear caterpillar has 13 segments. They can be easily identified in the above picture. Each one of these segments symbolizes one week of winter. The brown segments represent a mild week, and the black segments represent a harsh week. If the head area has more, then the beginning of winter will be the harshest. If the rear area has more, the end of winter will be the worst.

The thickness of the caterpillar’s hair is also an indication of the upcoming winter conditions. If it is dense, the winter will be colder. If it is sparse, the winter will be mild.

Giant Leopard Moth Caterpillar
Giant Leopard Moth Caterpillar

Giant Leopard Moth Caterpillar

A caterpillar often mistaken for the Woolly Bear is the giant leopard moth caterpillar. However, this caterpillar is completely covered with black hair and has red spiracles and inner segments. Every year, people get nervous when they see this caterpillar. They believe the winter is going to be horrible because the caterpillar is completely black with no brown.

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The Vermillion Festival

Woolly bear caterpillars are very popular in Ohio. So much so, the residents of Vermillion have held an annual “Wooly Bear Festival” since 1973. Until this year, of course, thanks to all the cancellations due to the Coronavirus. This festival usually lasts one day and includes a winter forecast, parade, and even woolly bear races.

Isabella Tiger Moth Caterpillar Woolly Bear Caterpillar
Isabella Tiger Moth Caterpillar

Science or Folklore?

How accurate are the woolly bears weather predictions? Not very accurate at all. Scientists have performed studies and have found out that the caterpillars’ bands are affected by other factors. These include the species, food source, natural conditions and age.

Just because there is no scientific evidence that the Woolly Bear caterpillar can predict the weather, does not mean they cannot. As many of us nature lovers know, animals and insects seem to know what is coming before we ever do.

Caterpillar Stuffed Animal Cute Plush Toy Caterpillar Wooly Bear the Orange and Black Snuggle Worm Cuddly Faux Fur Toy Small 5x14 Inches

So, if you want to believe in the folklore or not, is up to you. It does not hurt to check out the caterpillars and see what they might be telling you. Maybe they will be right. This year the caterpillars that I have found all have a large brown section so, here is hoping for a mild winter.

Isabella Tiger Moth Caterpillar Woolly Bear Caterpillar
Isabella Tiger Moth Caterpillar

2020-2021 Woolly Bear Winter Prediction

The caterpillar pictured above have 13 segments, 7.5 are black and 5.5 are brown. There are 5 dark stripes on the front end of the caterpillar and 2.5 on the rear. So, according to folklore the beginning of this winter should be harsh and the end of it not so bad.

The last caterpillar pictured is not the same caterpillar as the one pictured above it. However, they have the same markings. So, is it because of their diet? Maybe it is the species. Or is it possible that they can predict the weather and are in agreement?

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