Pest Folklore | HomeTeam Pest Defense

Can common household pests predict the weather?

Before there were weather apps on our smartphones, Doppler radar, or even a National Weather Service, people turned to folk wisdom for clues about weather projections. Common rodents and household bugs weren’t just pests; they were predictors of the weather. Here are a few examples of insect and weather-related sayings:

“When spiders’ webs in air do fly, the spell will soon be very dry.”

“If ants their walls do frequent build, rain will from the clouds be spilled.”

“See how high the hornet’s nest; ‘twill tell how high the snow will rest.”

Early sailors and farmers also looked to bug behavior for short-term weather predictions. If a spider abandoned its web, for example, that meant rain was imminent; spiders weaving their webs in the middle of the day indicated continued good weather. Just before rain, cockroaches would fly, ants got busy building up their mounds, and fireflies would glide low to the ground, according to folk wisdom.

The “Farmers’ Almanac” has included examples of long-term predictions related to insect behavior for centuries (literally; the first almanac was published in 1792). Some of the most relied-on signals of a harsh winter have been:

• Mice chewing furiously to get into homes.
• Crickets appearing on the hearth earlier than usual.
• Spiders spinning extra-large webs.
• Monarch butterflies migrating early.
• Ants marching in a line rather than meandering.
• Woolly bear caterpillars sporting mostly black “fur.”

Is it science or superstition?

Can household pests predict the weather? Do these weather proverbs hold up under the scrutiny of science? For the most part, scientists dismiss these beliefs as superstitions. But there is a correlation between the weather and the ways that insects, rodents, and other pests behave.

HomeTeam entomologist Russ Horton explains that weather patterns affect how and when insects mate, and that insect behavior can offer clues to when the current season is ending and the next is arriving. When the weather begins cooling in the fall, some insects prepare for “overwintering,” or waiting out the winter season (much like hibernation). Wasps, stink bugs and ladybugs look for shelter in attics or eaves. Nesting insects search for spots to build nests safe from the cold. Migrating insects, like monarch butterflies, will take off when the temperature changes.

As long-term weather patterns change, insect behavior patterns change too. Cricket activity is a sign of cooler weather. When football season arrives in the fall, crickets come out in droves. In the recent past, as the weather stayed warmer longer, HomeTeam professionals noticed pests like roaches and fire ants sticking around longer than usual as well.

On the other hand, bugs get busier as the weather turns warm. Termites and ants start coming out in the early spring. Bees, wasps and flies venture out when flowers are in bloom. When the weather turns rainy, earwigs and millipedes are driven out of their habitats in the soil – and into homes.

Barometric bugs

Science also suggests that in some cases insects are attuned to the weather. For example, one team of researchers observed that the mating patterns of some bugs may reflect and even predict changes in the weather. Meteorologists must use a barometer to track atmospheric pressure for signs of what weather is ahead. But some beetles, moths, and aphids may detect and react to changes in atmospheric pressure and become less amorous. One study suggested that potato aphids, for example, were less interested in mating when pressure changes heralded a storm.

And if you want to know the temperature outside, listen to the crickets! The more quickly crickets chirp, the warmer the temperature. Crickets’ chirps are a proven measure of temperature. Here’s the formula: Count the number of cricket chirps you hear in 14 seconds. Add 40, and you’ll get the approximate outside temperature.

All legend, little science

Despite scientific explanations for pest behavior, the length or severity of the next season isn’t predictable based on how rodents or insects act. Our HomeTeam entomologists helped us debunk common pest-related adages, and also validated those that hold some truth.

• Spiders spinning extra-large webs. Although not exactly a prediction of the severity of a winter, the size of a spider’s web may have some links to the weather. When the weather gets cooler, there are fewer bugs around and thus less prey available, so spiders may build wider webs to catch more prey. Web-weaving takes lots of energy, and spiders need to conserve more energy in the winter, so they build up their webs to get ready.
• Mice chewing furiously to get into the house. Similarly, rodents detect changes in weather conditions. As winter approaches, there’s less food available, and that drives mice into homes looking for food.
• The ants go marching. If ants march in a straight line, it has nothing to do with the weather. Some types of ants will trail due to pheromones; others don’t trail at all.
• Coloring of woolly bear caterpillars. Folklore says that the coloring of the woolly bear caterpillar (Pyrrharctia isabella) in autumn predicts the severity of the coming winter. Also common is the belief that the longer a woolly bear’s black bands are, the longer, colder, snowier, and more severe winter will be. This myth is so popular that it inspired an annual Woolly Bear Festival in Vermilion, Ohio, the brainchild of a longtime Cleveland-area TV weatherman. Of course, the truth is that a caterpillar can’t predict what Old Man Winter has in store for us. Its coloring is actually the result of how long the caterpillar has been feeding, its age and its species. The width of the banding may provide clues about current or past season growth, but it doesn’t tell you anything about the upcoming season.

The next time you see an insect, spider, or other “creepy-crawly,” check out what it’s doing! While they’re not reliable long-term forecasters, their behavior might give you a few clues about what’s happening with the weather – or maybe, just a chance to reflect on some fun weather proverbs from the past.

And, whatever the weather, if too many of these household pests are making their way into your home or yard, call HomeTeam for reliable and effective pest control service or rodent control service.