Tom Turpin
Professor of
Purdue University







Insect Weather Predictors

Everybody is interested in the weather. If we aren't talking about it, we are trying to predict it.

Today, weather forecasters use a variety of scientific tools and equipment, but that hasn't always been the case. There was a time when nature provided the primary information used in weather predictions. For instance, insects and insect behavior.

Flies, it is said, bite sore just prior to a rain. When rain is on the way, gnats swarm and flies collect on the screen door. Swallows also fly low just before a rain or a change in the weather. This is because the swallows are feeding on flying insects that also fly low just before a rain. Butterflies flying from the southwest also indicate the approach of rain.

Folklore holds that stepping on an ant will bring rain. Maybe that ancient belief gave rise to the Indian rain dance when some overzealous individual got into an ant nest!

Insects have been used to predict the onset of the seasons. It is said that a yellow butterfly flying in one's face indicates a frost within the next 10 days that is sufficient enough to turn the leaves the color of the butterfly. The first song of the dog day cicada means six weeks to frost. A Zuni Indian saying indicates, "When the white butterfly comes, comes also the summer.”

Where a butterfly chrysalid is suspended is said to indicate weather trends. If the chrysalid is on a heavy branch, expect rain. If it is found on the underside of slender branches, then we are in for a spell of fair weather.

Foraging behavior of bees gives a hint of weather to come. Someone put these ideas in a poem:

When bees to distance wing their flight,
Days are warm and skies are bright.
But when the flight ends near their home,
Stormy weather is sure to come.

(Hopefully the writer's observation of nature was better than his poetry.)

The insect really comes into its own in predicting the severity of winters. A harsh winter is sure to follow when bees lay up an unusually large store of honey. Hornets, it is said, build nests near the ground when a severe winter is expected.

The champion of the insects used to predict winter has to be the wooly-bear caterpillar. This fuzzy black caterpillar, with a reddish-brown band around its midsection, wanders around in the fall looking for a place to spend the winter. According to legend, the narrower the band, the longer the winter. However, don't sell the snowplow based on wide bands on wooly-bears; scientists say the width of the band has to do with what the caterpillar ate!


Writer: Tom Turpin
Editor: Carol McGrew