Birds & Blooms
Most of us are used to seeing backyard butterflies flutter and dip between blooms in bright sunny gardens, dining on the sweet nectar that gives them the energy they need to survive. Occasionally, though, you’ll find butterflies in totally unexpected places, like mud puddles or the sandy banks of a river—sometimes gathering in extremely large groups.
It may seem curious, but the butterflies are engaged in an activity known as puddling. A closer look will reveal they are likely males. “Male butterflies, just like any living creature, are trying to ensure they reproduce,” explains Ryan Fessenden of the Florida Museum of Natural History’s Butterfly Rainforest. “One of the ways they do that is by passing on nutrients, along with genetic material, to the females when they are mating.”
When butterflies mate, males transfer a spermatophore to the females. Think of this as a tiny package that holds just about everything a female needs to produce healthy fertilized eggs.
These spermatophores can be
very large relatively, making up as much as 10% of a male butterfly’s weight. Part of the package includes nutrients that help support the female butterfly’s health, making her offspring more likely to survive.
“Male butterflies gather those nutrients by drinking water from wet spots on the ground, collecting various minerals and nutrients such as sodium and amino acids,” Ryan says.
And it’s not just the mud that attracts butterflies. Like other animals, butterflies need salt in their diet, and they find it in some very unexpected spots.
“You may find a butterfly seeking out these valuable nutrients in other unusual locations, such as in tears on a crocodile or in sweat on human skin,” Ryan says.
They’re also drawn to less savory items such as decaying flesh and excrement. There’s even a group of moths in Central America that puddle on blood. Off-putting as it may seem, these behaviors are vital to their survival. That’s why you may see huge swarms of dozens or even hundreds of butterflies when a good puddling spot appears.
“The more males that can gather nutrients, the more success the species will have reproducing,” Ryan says. “So when a wet spot or puddle is found by one, other butterflies will notice and join in.”
Any type of butterfly can puddle, but it’s most common in members of the swallowtail family, sulphurs and whites. In particular, look for tiger swallowtails, red-spotted purples, white admirals, cabbage whites, and clouded and cloudless sulphurs at puddles. They are all there for one reason—to ensure they survive and thrive for many generations to come.
Jill Staake gardens for butterflies and has had more than a few land on her to drink some summertime sweat.