Butterflies are easy.
It’s a statement we naturalists make from time to time, and it refers to the fact that we need exert virtually no effort to get people interested in butterflies. Snakes and spiders, on the other hand, are tough, and slime molds are darn near impossible. But butterflies are easy.
So it was the other day when a mourning cloak butterfly suddenly appeared, fluttering along in the spring breeze. I was helping a friend with a prescribed burn on her property when another friend pointed up in amazement as the dark-winged jewel flew gently past. “Surely it’s too early for butterflies,” the friend said. But you know what? It’s not.
What my friend saw the other day was a mourning cloak, one of only a handful of butterflies in our area that hibernate as adults. (Other species spend the winter as eggs, larvae or pupae inside chrysalises.) When the days lengthen and temperatures begin to warm, mourning cloaks emerge from their winter shelters and begin their search for first, food, and soon, a mate.
Of these two necessities, food is probably the harder one to find. Flowers haven’t begun to bloom yet, so nectar isn’t an option. And while tree sap has begun to flow, unless a tree has been injured the sap isn’t likely to be very accessible. No need to worry though; mourning cloaks are programmed to survive. Decaying fruit may be a menu option, as are mud puddles and, believe it or not, animal droppings.
To be able to fly mourning cloaks must warm their bodies via basking—sitting with wings open, and held at an angle to maximize exposure to the sun. Their dark coloration aids in this endeavor and in fact gave rise to the insect’s common name. Dark brown, with a line of iridescent spots and a border of bright yellow, the butterfly’s wings were thought to resemble the cloaks worn by people “in mourning.”
You might think that a mourning cloak would want to stay warm all winter. We do, don’t we? Ah, but we don’t have the chemical makeup of a hibernating butterfly. As temperatures begin to cool in fall, mourning cloaks produce large amounts of sorbitol and other chemicals that serve as natural antifreeze.
People also are tempted to think that butterflies need help finding shelter for the winter. Remember when butterfly houses hit the market a few years back? The thinking was that the tall, decorative boxes with wide slits staggered along the front would provide “habitat” for butterflies needing a place to stay.
Research has since shown that butterfly boxes do indeed make great homes…but not for butterflies. In one study, 40 boxes were examined and found to be home to spiders, wasps, flies, ants and, in one instance, a white-footed mouse. Where were the butterflies? In their natural hibernation spots—under loose tree bark, leaf litter and brush piles.
The researchers concluded that butterfly houses function well as garden ornaments but do little to aid the survival of our native butterfly species. A better tactic for those wishing to help butterflies, said one scientist, would be to build a mud puddle.
Now that’s easy!
Pam Otto works for the St. Charles Park District and can be reached at potto@stcparks.org or 630-513-4346.