Can insects predict the weather? The strange folklore of nature’s tiny forecasters

Originally written by Leo S. 🙏🏼 in 2022. Updated 2026

Long before weather forecasts appeared on television screens or smartphones, people looked to the natural world for clues about what the sky might have in store. A sudden chorus of crickets, ants carrying grains of earth up the sides of their nests, or a spider’s web glistening in the morning dew could all be interpreted as signs of rain, sunshine or an approaching winter. Passed down through generations, these beliefs formed an informal kind of meteorology, shaped by close observation, seasonal rhythms and a healthy dose of imagination.
Even today, many of these sayings remain part of rural folklore. Some sound surprisingly plausible, others seem almost magical.
And while insects and other small animals cannot reliably replace a meteorologist, their behaviour can sometimes offer genuine clues about changes in their immediate environment. The challenge lies in distinguishing what nature actually reveals from what tradition has taught us to believe.

Consider the ant, an insect that has inspired an extraordinary number of weather predictions.
According to an old saying, high anthills in July foretell a hard winter, while ants frequently building up the walls of their nests supposedly signal rain. The height of a hornet’s nest is also said to reveal how deep the coming snow will be. These beliefs reflect an enduring human fascination with animals that appear to prepare for seasonal changes long before they arrive.
There are practical reasons why some of these observations might seem convincing.
Ants respond to moisture, temperature and conditions around their nests, and changes in their activity may reflect their immediate surroundings. Rain can also flood poorly protected nests, making shelter and drainage important to colony survival. Yet the height of an anthill or a hornet’s nest is not a dependable way to predict the severity of an entire winter. Nest construction depends on numerous factors, including the species, the site and the surrounding environment. A striking nest may be a fascinating sight, but it is no substitute for a forecast.

Bees, too, have earned a place in traditional weather lore.
One familiar rhyme claims that bees flying far from their hives promise warm days and clear skies, whereas those staying close to home herald an approaching storm. There is a kernel of plausibility here: honeybees are sensitive to temperature, wind and rainfall, all of which affect their ability to forage safely and efficiently. Cold, wet or windy conditions can discourage them from venturing out, while favourable weather allows longer journeys in search of nectar and pollen. However, their movements tell us more about conditions affecting the hive at that moment than about what the weather will be tomorrow.

Houseflies have a similarly persistent reputation. According to folklore, flies gathering indoors are a warning that rain is on the way. In reality, their behaviour can be influenced by temperature, humidity, light and changes in their surroundings. When conditions outside become less favourable, their movements may change accordingly. Such behaviour can coincide with an approaching weather system, but it does not establish that the insects can predict rainfall with any consistent accuracy.

Then there are crickets, whose chirping has long been associated with temperature. One traditional belief holds that the faster a cricket chirps, the warmer the air must be. Unlike many weather sayings, this one has a genuine scientific basis: in many cricket species, the rate of chirping increases with temperature within a certain range. The relationship is sufficiently consistent that, under suitable conditions, the calls of particular species can be used to estimate the surrounding air temperature.
The American physicist Amos Dolbear famously described this relationship in 1897, publishing an observation that became known as Dolbear’s law. By counting a cricket’s chirps over a set interval, it is possible to estimate the temperature approximately, provided the species and counting method are appropriate. It is not a universal thermometer, and different species behave differently, but it is a delightful example of how a familiar sound can reveal something measurable about the natural world. The old saying that crickets chirp faster when it is warmer is therefore grounded in biology, even if their songs cannot reliably tell us whether tomorrow will bring sunshine or a thunderstorm.

Spiders have inspired a different collection of weather omens. Their webs, delicate structures that appear almost weightless against the morning light, have been regarded as tiny atmospheric instruments. An old rhyme suggests that webs drifting through the air herald a spell of dry weather, while spider silk floating across the sky at sunset is said to predict frost overnight. Other traditions claim that spiders descend from their webs before rain or that unusually large webs in autumn foretell a cold winter.
Some of these observations have a plausible explanation, although the traditional predictions go further than the evidence allows.
Spiders respond to their surroundings, and the conditions in which they build, maintain or abandon their webs can be affected by temperature, humidity, wind and prey availability. Certain spiders also disperse by releasing silk strands that catch the breeze, a behaviour known as ballooning. The sight of fine silk floating through the air is real, but it does not guarantee that a long period of dry weather is about to begin.
Dew-covered webs offer another intriguing example. When a web glistens with moisture that subsequently evaporates, it may indicate that conditions are becoming favourable for drying. Clearer skies, sunlight and relatively dry air can all contribute to that process. Yet the observation remains local and conditional: a web drying in the morning cannot provide a reliable forecast for every place or for the entire day. As with many traditional weather signs, the most useful information lies in the immediate conditions rather than in predictions extending far into the future.

Perhaps no creature has become more famous as a folk meteorologist than the woolly bear caterpillar, the fuzzy, black-and-rust-coloured larva of the Isabella tiger moth found in North America. Each autumn, these caterpillars can be spotted crossing paths, gardens and roads as they search for sheltered places to spend the winter. Their distinctive bands have inspired a popular belief that they can reveal how harsh the coming season will be.
According to the best-known version of the legend, a caterpillar with broad black bands predicts a long, bitter winter, while one with a wider reddish-brown band promises milder conditions. Some versions go further, suggesting that the position of the dark bands indicates when the coldest part of winter will arrive. The caterpillar’s thirteen body segments have even been said to correspond to the thirteen weeks of winter.
The story became particularly popular in the United States following a small observation made in 1948 by entomologist Howard Curran, associated with the American Museum of Natural History. His examination of a limited number of caterpillars attracted newspaper attention, helping transform an old piece of folklore into a recurring autumn tradition. Today, woolly bear festivals in parts of the United States celebrate the caterpillars with races, family activities and playful seasonal predictions.
Unfortunately for anyone hoping to consult a caterpillar before buying a winter coat, scientific evidence does not support the idea that its colour bands can reliably forecast the winter ahead. The pattern changes as the caterpillar grows and moults, and its appearance is influenced by its stage of development and growing conditions. Rather than predicting future temperatures, its markings tell us more about the animal’s own life and recent history.
The real story is arguably more remarkable. Woolly bear caterpillars can survive freezing conditions by tolerating the formation of ice in parts of their bodies, a specialised adaptation that allows them to endure winter and resume development when conditions improve. Their survival strategy is a genuine biological marvel, even if their supposed forecasting abilities belong to folklore.

Nor are insects and spiders the only small creatures recruited into humanity’s informal weather service. Frogs and other amphibians have long been associated with rain. The louder the frogs, according to one traditional saying, the greater the rainfall to come; evening choruses, by contrast, are sometimes interpreted as a promise of fair weather the following day. Their calls are closely linked to reproduction and environmental conditions, and rainfall can create favourable circumstances for breeding in many species. Changes in temperature, humidity and water availability can also influence calling activity. Nevertheless, a noisy pond does not necessarily mean that a storm is imminent.

Snakeskin, meanwhile, appears in a more curious piece of traditional weather magic: hanging a shed skin outdoors is said to bring rain. Unlike the observations concerning cricket chirps or animal activity, this belief has no established scientific mechanism connecting the skin itself to rainfall. It belongs to the more superstitious side of weather folklore, where symbolic associations and inherited customs take precedence over measurable cause and effect.

Taken together, these traditions reveal something important about the relationship between people and the natural world.
For generations, farmers, gardeners and travellers paid close attention to the creatures around them because weather shaped nearly every aspect of daily life. Observations were repeated, remembered and turned into rhymes that were easy to pass from one generation to the next. Some captured genuine biological relationships; others may have been reinforced by coincidence, selective memory or the human tendency to notice predictions that appear to come true.
Modern science does not require us to dismiss these traditions entirely. Instead, it invites us to look at them more carefully.
A cricket’s chirp can offer a rough indication of temperature, and a bee’s reluctance to leave its hive may reflect unfavourable conditions. But a hornet’s nest cannot tell us how much snow will fall months from now, and no woolly bear can reveal the severity of an approaching winter simply through its stripes.
Perhaps the enduring appeal of insect weather folklore lies precisely in this mixture of observation and mystery. It encourages us to slow down, listen to the evening chorus, notice a spider’s silk catching the light and watch ants working beneath our feet. These small encounters remind us that the atmosphere is not separate from the living world: temperature, moisture and wind influence the behaviour of countless creatures, often in ways we barely notice.
So the next time crickets begin their evening song or a spider’s web sparkles with dew, take a moment to look more closely. You may not discover tomorrow’s forecast, but you will find something just as fascinating: a glimpse into the subtle ways animals respond to the world around them, and the centuries-old human desire to understand what nature might be telling us.