What Do Worms, Frogs, Bees and Bugs Do When It Rains?

Rain changes a backyard almost immediately. Bees disappear from flowers. Frogs suddenly seem much louder. Ants scramble for cover. And after a good soaking, earthworms appear on sidewalks and driveways as if they have all decided to come aboveground at once.

These animals aren't all responding to rain for the same reason. For some, wet weather creates an opportunity. For others, it's something to avoid. And a few familiar explanations for rainy-day animal behavior aren't quite as simple as we've been led to believe.

Why Do Worms Come Out When It Rains?

You've probably heard that earthworms crawl onto sidewalks after rain because their underground tunnels are filling with water and they'll drown if they don't escape.

That's not the whole story.

Earthworms breathe through their skin, which needs to remain moist for oxygen to pass through it. Many earthworm species can survive for quite a while in oxygen-rich water, so a wet burrow doesn't necessarily send them racing for the surface to avoid drowning.

Rain does, however, create excellent conditions for traveling aboveground. Normally, an earthworm exposed to dry air risks losing moisture through its skin. During and after rain, the ground surface is wet and humidity is high, allowing worms to move across the surface much more safely.

That may help them reach new feeding areas or find mates without having to tunnel through soil the entire way. Heavy rain can also reduce oxygen levels in waterlogged soil, which may encourage some species to surface. What happens underground depends partly on how rain moves through soil and eventually becomes groundwater.

Unfortunately, pavement creates a problem. A worm that crawls onto a sidewalk while everything is wet may still be there when the sun comes out and the pavement begins to dry. What was briefly a safe route can quickly become a dangerous place for an animal that depends on moist skin.

Why Do Frogs Get So Loud When It Rains?

For many frogs and toads, rain is less of an inconvenience and more of an invitation.

Amphibians have permeable skin that loses moisture easily, so damp conditions make it safer for them to move around. Rain can also create temporary pools and fill ponds and wetlands—the very places many species need for breeding.

That's why a warm spring or summer rain can suddenly produce an impressive chorus from a pond that seemed quiet earlier in the day. Male frogs call to attract females, and favorable wet conditions can trigger a burst of breeding activity.

Different species make different calls, so what sounds like one enormous chorus may actually be several species advertising themselves at the same time.

Fun fact: Frogs don't just say "ribbit." Depending on the species, their calls can sound like trills, peeps, chuckles, snores, plucked strings and even the quacking of ducks.

Where Do Bees Go When It Rains?

Rain and flying don't mix particularly well for bees.

A honey bee caught in a light shower may continue flying, but heavier rain makes flight difficult. Raindrops are large compared with a bee, wet wings don't perform as well, and strong winds add another challenge. When poor weather approaches, honey bees generally return to the hive or remain inside rather than heading out to forage.

That doesn't mean every bee has a hive to go home to. Most bee species are solitary rather than social. Depending on the species, a solitary bee may shelter in an underground nest, a hollow plant stem, a small cavity or another protected location.

Rainy weather can therefore make a flower garden seem strangely empty. When the sun returns and flowers dry, bee activity often picks up again quickly.

Can Bees Tell That Rain Is Coming?

Bees can respond to changes in their environment associated with approaching weather, including shifts in light, temperature, humidity, wind and atmospheric pressure. Studies suggest that some bees alter their foraging behavior when bad weather is approaching.

That makes practical sense. A bee that ventures too far from shelter just before a heavy storm risks being caught in conditions that make flying difficult or impossible.

It can look as though bees are predicting the weather. More accurately, they are responding to environmental signals that arrive before the rain itself.

What Happens to Butterflies When It Rains?

Butterflies are another group that generally sits out bad weather.

Their large wings work well in calm, warm conditions but can make flying difficult in strong wind and heavy rain. Butterflies often shelter beneath leaves, within dense vegetation, in tree crevices or in other protected places.

Cool temperatures can be just as important as rain. Butterflies depend on external heat to warm their bodies enough for effective flight, which is why a cold, rainy morning can leave them almost completely inactive.

Once conditions improve, they may spread their wings in the sun to warm up before becoming active again.

What Do Ants Do During Heavy Rain?

Ant colonies face a different problem: their homes are often underground.

Many ant nests are surprisingly well suited to dealing with ordinary rain. The shape of the entrance, the structure of underground tunnels and the surrounding soil can help prevent water from simply pouring into the colony. Some species build raised entrances or close openings when conditions become unfavorable.

During extreme rainfall or flooding, however, ants may need more dramatic solutions. How quickly rain falls can matter as much as the total amount: a short, intense downpour can affect the ground very differently from hours of gentle rain. Some ants move larvae, pupae and queens to safer parts of the nest or relocate altogether.

Fire ants are famous for an especially remarkable response to flooding. Workers can link their bodies together to form floating rafts carrying the colony—including the queen—until they reach dry ground.

Fun fact: A floating fire-ant raft isn't just a random pile of ants. The ants grip one another with their legs and jaws, creating a living structure that can remain afloat while the colony is displaced by floodwater.

Where Do Mosquitoes Go in the Rain?

You might expect mosquitoes to be helpless in a rainstorm. After all, a raindrop can weigh many times more than a mosquito.

Yet mosquitoes can survive collisions with raindrops surprisingly well. Their extremely low mass works in their favor: instead of absorbing the full force of a falling drop, a mosquito may be pushed along with it before escaping.

That doesn't mean mosquitoes happily cruise around in a downpour. Heavy rain and strong wind can interfere with flight, so they often seek sheltered areas in vegetation and other protected spots.

The bigger effect may come later. Standing water left behind by rain can create breeding habitat for mosquitoes. Depending on the species, water collected in containers, tree holes, clogged gutters, puddles and other small reservoirs can become places where mosquito larvae develop.

So the mosquito consequences of a storm may become much more noticeable days after the rain has stopped.

What About Other Insects?

For small insects, a rainstorm can be a major physical event. A single raindrop is enormous relative to the body of an aphid, beetle or tiny fly.

Many insects avoid the worst of it by moving beneath leaves, into bark crevices, under rocks, into soil or deep within vegetation. The underside of a leaf can provide a surprisingly effective miniature roof.

Others are adapted to wet conditions and become more active when humidity rises. Slugs and snails, while not insects, are familiar examples. Their bodies lose moisture easily, so rainy conditions allow them to travel and feed with much less risk of drying out.

This is one reason a garden can seem to contain an entirely different collection of creatures after dark on a wet evening.

Rain Doesn't Mean the Same Thing to Every Animal

To us, rain is usually described simply as weather. To a small animal, it can completely change the environment.

For an earthworm, wet ground may provide a rare opportunity to travel safely across the surface. For a frog, a warm rain may signal ideal breeding conditions. For a bee or butterfly, the same storm may mean it's time to stop flying and find shelter. For mosquitoes, the puddles left behind can create the next generation's nursery.

And all of those responses begin with what happens after a raindrop reaches the ground. Some water soaks into the soil, some runs off, some collects in low spots and some returns to the atmosphere—the next stage in a raindrop's journey through the water cycle.

That's part of what makes a rainy backyard so interesting. The amount in the rain gauge tells you how much water fell, but all around it, that water is changing where animals move, when they feed, where they reproduce and what they do next.

The next time a storm passes, take another look outside. The rain may be over for you, but for many of the smallest creatures in your yard, the interesting part has just begun.