Mourning cloaks tough out the winter
April 17 of this year started quite well for me. I had found a parking spot at the Forum lot. That, in itself, was an accomplishment. But while striding across the parking lot with a little extra spring in my step, a small winged creature flitted across my path. It was the first one I'd seen since last fall. Its unmistakable markings were that of a mourning cloak (Nympalis antiopa) butterfly.
Even as a kid growing up in West Fargo, the mourning cloak was one of the most easily identified butterflies I and my buddies encountered during the summer. Dr. Ronald Royer wrote of the mourning cloak in his book, "Butterflies of North Dakota," referring to it as "...one of the most distinctive butterflies in the world. It cannot be confused with any other species."
It has a remarkably rich brown color to its wings with an outer border of powder blue spots embedded in a darker brown area and a fairly wide, creamy white margin on the edges. Again, it is unmistakable.
Equally unmistakable is the fact that it is nearly always the first butterfly reported in the spring here in the Red River Valley. I've seen it quite often with snow still on the ground. From Kenn Kaufmann's book, "Butterflies of North America," comes this accurate phrase: "For winter-weary northerners, few sights can be as welcome as that of the first mourning cloak..."
The reason this particular insect is so ready to tackle the vagaries of our spring conditions is this wispy little thing over-winters as an adult butterfly. Sound crazy? I think so too. But it has evolved a strategy which puts it among the longest lived butterflies in the world - up to eleven months.
Just how this happens is amazing. Dr. Gerald Fauske, NDSU, is the collection manager of the North Dakota state insect collection. He said, "Butterflies that hibernate as adults survive the winter by reducing the amount of water in their haemolymph (blood) and, most importantly, by creating their own anti-freeze (ethylene glycol) in their blood and cells to reduce the freezing point temperature." How cool is that? Here's a little butterfly with the ability to pump the same stuff we put in our radiators through its own body.
After emerging in spring, the mourning cloak usually looks ragged and worn. (I imagine we would too if we spent the winters under a piece of bark outside). The adults then go about feeding and mating to produce a new batch of fresh butterflies by July. It's this generation that is the more boldly and richly colored one.
Mourning cloaks are members of a huge and varied family of butterflies called Nymphalidae. The common name for this group is "brushfoots." I asked Fauske why that name. He said, "Because the forelegs of the males in all species, and of the females in all but 12 species worldwide, are atrophied." In other words, the legs are a mere brushy stump with sensory hairs. It's used for cleaning the eyes and for tasting. Fauske said, "They often stomp when sitting on a flower." That stomping is the insect tasting potential food.
For flower gardeners, this butterfly is not a very reliable visitor. Its preferred food is tree sap. Even further, oak tree sap. It also feeds on fermenting fruit and will only occasionally visit flowers. I've had great luck attracting mourning cloaks to my back yard by setting out melon rinds.
Before we go bragging about how special we are to have such a neat butterfly in our area, consider this: The species is circumpolar, meaning it is also found in Asia and Europe (it's known as the Camberwell beauty in England). Moreover, it inhabits virtually the entire North American continent. But we Americans may be able to claim first rights of a sort. Fauske feels the mourning cloak probably evolved first in North America. For evidence he cites the fact that its closest relative is found in the mountains of northern Mexico. He said, "This Mexican species strongly resembles the
mourning cloak in size, shape, and some color."
Most butterfly references will tell you this is mostly a forest butterfly. True, but it can be found almost anywhere, especially among willows along watercourses. And take my advice later this summer. Put your used melon rinds out in the garden and I almost guarantee a visit from a mourning cloak