Insects, livestock and wildlife don’t really predict weather

wooly bear

Do woolly bear caterpillars mean a bad winter is coming? Do cows lie down before rain? Does a large spider web mean cold weather?

Have you ever wondered if these claims are actually true? If so, you’ve come to the right place. As legend has it, you can tell bad weather is brewing just by looking at the behavior and physical features of animals and insects.

You have surely heard someone point out a woolly bear caterpillar and say, “Ope, looks like a bad winter is ahead,” or have heard your Grandpa say, “Rain’s comin’ — the cows are lying down.” These claims are myths. A myth is a traditional, ancient story that may be based on factual origins, but is often completely fictional. Unfortunately, these myths have been busted.

These types of myths and weather predictions fall under pseudoscience, which is a collection of beliefs or practices mistakenly regarded as being based on scientific method. They often occur when people have thought the same thing for years, and when the thought is such a popular, widespread idea that it eventually becomes considered true.

So, if animals and insects can’t actually predict the weather, why do people think they can?

Woolly bear caterpillar

Perhaps the reason why this myth exists is because we start to see woolly bears emerge around fall. This is not because they are meteorologists, but rather because they are leaving areas where they find food in the summer, in preparation to find a dark, sheltered place to hibernate.

The color and size variation of the bands on the caterpillar correlates to its age and feeding habitats. The caterpillar’s colors vary both in the larval and adult stage. The caterpillars molt six times before they are fully grown, causing the band to become more brown and less black with age.

Although these little creatures can’t tell us the predicted winter forecast, they do have a cool feature that helps them to survive very cold, hazardous winters. Woolly bears produce a substance called glycerol.

As weather gets colder, the caterpillars slowly freeze but the glycerol helps to prevent their inside cells from freezing. This works much in the same way that antifreeze works in a vehicle. Eventually, the woolly bear caterpillar will turn into an Isabella Tiger Moth.

Cows lying down

Multiple different theories exist for this old myth. Some people believe that cows can sense increasing air moisture and will lay down to get a dry patch of grass. Others think that a cow will lie down to settle their stomachs after a full meal. Some believe that their four-chambered stomachs are sensitive to changes in atmospheric pressure brought on by rainfall.

Cows also tend to stand in hot weather, exposing more skin and allowing them to cool off faster. When rain is coming, the temperature drops, so many think that this is why cows predict rainy weather.

Regardless of all of these reasons, there is no scientific evidence for this weather myth. The most likely reasoning for this occurrence is that cows spend a lot of time lying down, either to rest or chew their cud, so when rain is coming there’s a 50/50 chance that they will be lying down. Cows also tend to mimic each other’s behavior so when one lies down, the whole herd might follow.

Winter weather myths

Although these myths have been busted, it is still fun to use them to guess the coming winter weather. There are several other common winter weather myths.

Some believe that when deer are in gray coat in October, you should expect a severe winter. Some think spiders spin larger than usual webs when colder weather is near. Others predict cold winters based on pigs gathering leaves and straws in the fall, or if rabbits are fat in October and November.

Other winter myths include that thicker than normal corn husks mean a cold winter, thick hair on the nape of a cow’s neck means cold months ahead or the less snakes you see, the worse winter will be.

Some myths suggest that geese and ducks leaving early, or that muskrats burrowing holes high on the riverbank, mean winter is coming. Finally, some say, “see how high the hornet’s nest, it will tell how high the snow will rest.”


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Becca Theaker is the Captina Creek Watershed coordinator at the Belmont Soil and Water Conservation District. She has a bachelor's degree in biology from Bethany College and is working on her master's degree in environmental science from Duquesne University.



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