A Mourning Cloak butterfly sips sap from our dying ash tree...

In our backyard we have a huge weeping willow tree and several birches, so I always hoped Mourning Cloak (Nymphalis antiopa) butterflies would show up. Both of these tree species are host plants for the butterflies, but it took our dying ash tree to finally lure the beautiful butterflies in...

A Mourning Cloak (Nymphalis antiopa) butterfly sips from a sap flow on our ash tree. Emerald Ash Borers have left their D-shaped holes all over our tree, and sap flows are everywhere. The only (short-lived) benefit of the infestation is an abundance of butterflies feasting on the sap, especially butterflies I don't normally see in our backyard, such as this Mourning Cloak. (Click here for an older post on the Emerald Ash Borer.)

I photographed this Mourning Cloak butterfly at about 4:30 in the afternoon. The sun was bright and washed out the butterfly's color. Here the butterfly appears to be trimmed in white, but really the edge is yellow. The bright light also brought out a reddish cast on the wings, but when not in bright light, the dorsal side of the butterfly looks more like a dark brown or velvety black. Against the black, the border is noticeably more yellow. The same shade of iridescent blue spots show in dark or bright light. 

Morning Cloak butterflies are called "brush-footed butterflies" or "four-footed butterflies" (family Nymphalidae). They have six legs like any other insect, but you can only see four of the legs. The other two are very small and resemble brushes. They are tucked up underneath the butterfly's "chin," and are not used for walking or perching. To read a little more about brush-footed butterflies, click here.

The ventral side of the Mourning Cloak butterfly looks wrinkled and bark-like. The dark, black color helps it blend into the tree bark. Mourning Cloaks love tree sap, so it's great camouflage. Additionally, this photo clearly shows how the butterfly looks like it only has four legs. The last two legs are small and brush-like, and make the butterfly look like it always needs a shave! 

The beautiful dorsal markings of a Mourning Cloak butterfly

Mourning Cloak butterflies undergo aestivation—a type of hibernation sometimes called "summer sleep." Mourning Cloaks like cooler temps. In the summer during hot and dry weather, the butterflies will go into aestivation and do not resume feeding until the cooler temperatures of fall return. Saturday was our first cool day of the season. Rain on Friday pushed in a much-needed cool front, and two Mourning Cloaks took to the wing on Saturday in our yard. (Source: "The Life Cycles of Butterflies," by Judy Burris and Wayne Richards, pg 138.)

A Mourning Cloak butterfly tucks itself up into a cedar tree for the evening. I was surprised as I watched it land on the tree and then slowly crawl deeper and deeper into it. By the time it was all the way tucked in, I couldn't see it anymore. Mourning Cloaks are one of the longest-lived butterflies in Ohio (can live 8-10 months). They overwinter here by hibernating through the winter. I'll have to keep my eye on this tree. It is well protected and would be an ideal place to hibernate.

In the spring, Mourning Cloaks are one of the first butterflies to take flight, and I have seen them flitting on sunny March days when snow is still on the ground! Since they are dark, they bask in the sun to raise their body temperatures for flight. They are solar powered on those cold days! Being sap lovers instead of flower nectar lovers helps these butterflies because they have a ready food source as soon as the sap starts to flow. Mourning Cloaks also love to feed off rotting fruit. This summer, I started a little area in my "wild patch" part of the yard where I would dump fruit that had started to turn before we could eat it. I put it out there for the hummingbirds, because I know they love to nab fruit flies from the air, but maybe the little fruit dump helped to lure these butterflies in too.