Can Moths Swim?

Out of more than 160,000 different species of moths, you’d think that there would be some species that evolved to breathe and swim underwater or even read minds. Well, some of them can swim, let’s just hope they don’t develop the mind-reading shtick anytime soon.

Can moths swim? There are almost 50 species of moths that are aquatic moths and spend at least some time underwater, either as larvae or adult moths. Truly aquatic moth species can be found only among the Crambidae, Cosmopterigidae, and Erebidae families, while semi-aquatic forms associated with amphibious or marsh plants are known in thirteen other families.

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How Do Moths Swim?

Now that we know that some moths can swim, let’s dive in and find out how they do it.

The aquatic moth will lay eggs underwater on rocks or vegetation. The eggs will stay there (unless they get eaten) for 6-14 days and then they’ll hatch.

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The hatched caterpillars create a case from leaf pieces and use silk to keep these pieces of leaves together to protect themselves. They will carry around this case for the entirety of their nymphal life and will feed
on aquatic vegetation.

The caterpillar pupates inside of this case by spinning a silk cocoon and attaches itself to a rock or plant material.
When the pupa is fully developed, the adult moth will emerge. It will swim using both its legs and wings to the surface of the water where it will crawl out of the water to dry its wings and find a mate.

The mated female moth will dive back down into the water where she will lay her eggs.

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She also has waterproof hairs, which are called hydrofuge hairs, on her wings and her body that will hold air around her creating a plastron.

A plastron is a bubble of air that dissolved oxygen from the water will diffuse into. She can breathe underwater using this air bubble!


The moth can actually crawl back to the surface of the water and fly away because she was completely surrounded by air the whole time that she was underwater. Although, most females will stay underwater, lay all of their eggs, and then become fish food.

If we could utilize this technology, there would be no need for oxygen tanks while scuba diving!

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