Science Explains Why So Many Damn Worms Come Out After It Rains

"There's no way to avoid them. Why would you want to?"

Flickr / Kurayba

A rainstorm necessitates more than an umbrella for fellow worm-fearers who live in soil-heavy environments. If the way that earthworms slither and coil their way to the surface and splay themselves across the wet concrete makes you queasy, you might want to plan some extra transit time or even take the damn day off.

Because if rainfall is heavy enough, then best believe that worms are going to be on the sidewalk and out to play. Unfortunately for those who dread the wriggling little freaks, it’s just what they do, according to Rhonda Sherman, a composting expert and an extension specialist at North Carolina State University’s Department of Horticultural Science.

According to Sherman, worms emerge when it rains in order to enter a more moist environment, which allows them to take in more oxygen. Coincidentally, entering a moist environment with a lot of worms sounds like a waking nightmare.

“Worms don’t have lungs and instead breathe through their skin; their skin must stay moist for oxygen to pass through it,” Sherman tells Inverse.

“When it’s raining, earthworms can move farther across the surface of the soil than through it underground.”

So, at least for the duration of precipitation, what looks like a worm massacre is actually more like a creepy crawly beach day, according to Sherman. “A lot of people assume that earthworms come out of their burrows when it rains because they are drowning. But they can’t drown like humans and can stay completely submerged in water for several days if there is oxygen in the water. “

But after the sun starts to shine again, those thirsty worms are in danger of getting trapped aboveground, as exposure to bright sunlight can temporarily paralyze them. “So, a worm comes to the surface while it’s raining, then the sun comes out and the water on the sidewalk evaporates quickly. The worm’s skin is getting drier and it can’t move because of the light, so it will dry up and die,” Sherman warned.

She recommended that anyone looking to assist worms in their time of need do so “by gently picking it up and putting it back in the grass or leaves so it will be shielded from the sun and go back underground.

But if you aren’t a worm fan, like the girls I knew in college who would skip class on rainy days to escape the worms, Sherman has some bad news for you. “The worms are going to come out when it rains, so there’s no way to avoid them,” she said. “Why would you want to?”

I can think of a couple reasons.

This velvet worm ain’t messing around! Check out this video about one of the fiercest predators on the planet.

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