A reader wrote to us on the All About Worms Facebook page about the prospect of reviving a dried-out worm with water. If gotten to soon enough, she asked, could a worm that is rapidly drying out on the sidewalk be resuscitated with water? More precisely, she asked about “red inch garden worms,” which we take to mean some type of inchworm, so she is technically asking about reviving dried-out caterpillars with water, not worms (because inchworms, being the larval form of geometer moths, are caterpillars). This actually changes things a bit, as caterpillars aren’t as susceptible to drying out as worms, but we’ll address both issues at once. So, the whole question before us is: can you revive worms or caterpillars that are dried-out with water?

Like all animals, worms need water to survive, and worms in particular are prone to desiccation. This is why they rarely come out during the day except after it rains, when you’ll likely see lots of long skinny worms out and about. They stay in moist soil during the day, which is where they absorb water into their bodies, and occasionally come out at night if necessary. Caterpillars are a little different. They don’t get their water from moist soil, but rather through the plant matter they eat. (We should briefly note that the reader was giving water and mud to an inchworm she found on the sidewalk, and while the soil might have helped protect the caterpillar from the sun, it wouldn’t really serve as source of moisture to a caterpillar in the way it would serve as a source of moisture to a worm.) Essentially, all caterpillars do is eat, so they are constantly taking water into their bodies and generally don’t live with the constant threat of drying out. It not uncommon to see dried-out worms on the sidewalk or road; you rarely, if ever, see dried-out caterpillars, however. At the end of the day, though, both worms and caterpillars need water to survive, and both could dry out if stranded on the sidewalk.

Given that caterpillars get their water from leaves and other plant matter, it is unclear what pouring water on them would do for their internal moisture level. Intuitively, it seems like this would help, and it certainly wouldn’t appear to cause any harm (unless of course you pour so much on them that they drown, but that would require a lot of water). Things that are drying out need water, plain and simple, and even if a caterpillar needs to ingest plants to get water to sate its “thirst,” it seems like pouring water on it would at least buy it some time. If every last bit of water is being sucked out of a caterpillar by the sun, then adding water to it would at least retard the desiccation. As for worms, we are certain pouring water on them would help, as would throwing a little mud over them. In doing so, you are essentially recreating their ideal environment – moist soil – and protecting it from the sun.

We will conclude by addressing our reader’s precise question: can you actually revive a worm or caterpillar with water? Basically, all we can say about this matter is that it depends on what is meant by “revive.” Obviously, you can’t bring something back from the dead, and you probably can’t bring back a caterpillar or worm that is essentially fully dehydrated and on the cusp of death. This is probably especially true in the case of a caterpillar, as it is not clear what pouring water on them would even do (apart from slowing down the rate of desiccation). On the other hand, giving some water to a worm or caterpillar that is drying out, but is not yet in dire straits, would help it, although it is unclear if this constitutes a full-blown revival. In any case, we hope we have helped our reader with her question, and applaud her compassion for the poor inchworm she came across. Hopefully her resuscitation was successful.

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