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Tuesday, July 11, 2017

Mourning Cloak Butterfly – Nymphalis antiopa


Mourning Cloak butterfly (Nymphalis antiopa): Mother Nature's Backyard

 
For the past two summers, the numbers and species of butterflies in S. California gardens have been abnormally low.  This year, with a wet winter easing the drought, many butterflies have returned.  We were particularly worried about the Mourning Cloak, a butterfly rarely sighted in our area in recent years.  We’re happy to report that the numbers of Nymphalis antiopa – in Preserves as well as gardens – are up again this summer in California.   The scientific name is pronounced nim-FAL-is  an-tee-OH-puh.

Growing up in S. California in the 1950’s and ‘60’s, Mourning Cloaks were a very common sight.  We searched for the more ‘exotic’ butterflies in our wanderings; Mourning Cloaks were hardly worth the effort.  Adulthood (and loss of butterfly habitat and numbers) have brought a new appreciation for these unique and beautiful insects.  We hope you enjoy them as much as we do.

Mourning Cloak (Nymphalis antiopa) : perched on
 Purple sage, Redondo Beach, CA
 
Mourning Cloaks have a huge natural range.  They are common throughout N. America, Europe, north-central Asia and Mexico. They were first defined by Linnaeus in 1758 (yes, this butterfly is common in Scandinavia!) [1]. In Great Britain, these butterflies are called ‘Camberwell Beauties’; they do not over-winter there and must migrate from Scandinavia and the continent [1].  They are known as Mourning Cloaks in most of Europe and N. America [2] and are the Montana state butterfly.

Mourning Cloaks belong to the Brushfoot butterfly family.  The Nymphalidae include several local favorites: the Lorquin’s Admiral, the Common Buckeye, the Red Admiral, the Gulf Fritillary and the West Coast, Painted and American Lady butterflies.  Our gardens would be far less interesting without the Brushfoots.    They are relatively large, brightly colored and fun to watch.
 

Mourning Cloak (Nymphalis antiopa) : on Grindelia hisutula
 
Nymphalis antiopa is a medium-large butterfly, with a wingspan of 2 ¼ to 4 inches (6-10 cm.).  Mourning cloaks are the only large, dark brown butterfly in local gardens; the Metalmarks and Duskywings (also brown) are much smaller.   Males and females look basically the same.

Mourning Cloak (Nymphalis antiopa) : underside
 
Mourning Cloak : excellent camouflage
 

The undersides of both sets of wings are a dark, rough-appearing brown, edged with light tan.  The wing margins are not smooth, but jagged.  All of this provides good camouflage in a variety of situations.  Mourning cloaks can virtually disappear on the dark trunks of trees.  But they are equally able to blend in when perched on local shrubs (see above).   They are particularly difficult to spot in the light and shadow of some of our native plants.   This is a good thing: camouflage is an important way Mourning Cloaks evade predatory insects (dragonflies), birds, lizards and others.

Mourning Cloak (Nymphalis antiopa) : upperside
 
In contrast to the lower side, the upper side of this species is very attractive and colorful.  The main wing color is a rich chocolate or mahogany brown.  The margins are banded with light tan-yellow, a nice contrast with the brown.  The pale margins are bordered inside by a darker brown band, dotted with pale, iridescent blue-lavender spots.  The entire effect is lovely and refined.   This butterfly’s common name is said to describe the butterfly’s appearance: a dark mourning cloak, covering a pale dress or petticoat [2].  


Mourning Cloak (Nymphalis antiopa) : note body features
 
But the visual treats don’t stop there.  Look carefully at the close-up above.  Admire the compound eye; no wonder they’re so hard to sneak up on!   Note the stout legs, used to grasp and move around a perch. Photographs allow you to fully appreciate an insect’s intricate beauty. Nymphalis antiopa appears to have only two sets of legs.  But look closely to see the short, hairy front leg.  This ‘brush foot’ gives the Nymphalidae their common name – Brush-foot butterflies.

Notice the stout facial and thorax (mid-section) bristles and the unusual face shape.   Mourning cloak adults have an unusual diet for butterflies: for the most part they eat sap and decaying fruit, although they will visit early-blooming trees (like willows) or summer-fall blooming members of the Sunflower family [4]. Like other butterflies, they extract salts and minerals from mud.  Not surprisingly, Morning Cloaks are not an important pollinator species.

Adult Mourning Cloaks over-winter as adults.  The Mourning Cloak season begins with the emergence of adults from hibernation in the spring.  In the warm winters of S. California, emergence can be as early as January; you can see this butterfly in any month in local preserves and gardens.  But they are most frequently spotted in spring and late summer/fall.   Adults live up to 12 months – one of the longest lifespans of any N. American butterfly [2, 5].

Willows (Salix species) : larval food for
 Mourning Cloak (Nymphalis antiopa)
 
Nymphalis antiopa is native to forests and woodland areas.  But it can be found where ever there are trees that supply its larval food, including local wetlands, riparian woodlands, parks and neighborhoods.  Larval food trees include willows (Salix species), aspens and cottonwoods (Populus species), American elm (Ulmus), hackberry (Celtis spp.), hawthorn, wild rose, mulberry, birches (Betula species) and alders (Alnus species).   The frequent occurrence of these host species explains the widespread appearance of Mourning Cloaks in wild and urban settings.

Morning cloaks mate in the spring, but there may be multiple broods (a second generation) in some areas, including S. California [3, 4].  Males choose a high perch to display to passing females or fly in search of mates.  Males mate with several females, and there is strong competition for choice sites.  For more details on courtship behaviors see references 2, 3. 
 

Mourning Cloak (Nymphalis antiopa) : perched male
 
The males are highly territorial and will fiercely defend their territory from other males, other butterflies (including the large Swallowtails), hummingbirds and even humans.  We’ve seen them harass Scrub Jays and even had one head-butt our hand.  That’s quite a butterfly – willing to take on a human!

After an aerial mating, females lay a cluster of eggs around a host plant twig.  Clusters contain small eggs that start pale yellow-green and mature to black (see reference 6 for a good picture).   The female dies after laying her last batch of eggs. 

The larvae emerge after about 10 days, and will go through five larval stages (instars) before emerging as fully developed caterpillars.  Each instar but the first  (which is pale, with a dark head) looks fairly similar: a spiny, dark caterpillar with a line of red dots down the back.  The larvae have a distinct appearance: see reference 4 for excellent photos of all stages of development.

The larvae often remain together through much of their development.  Like all caterpillars, they are voracious eaters. They must be, to grow from a tiny egg to nearly 2 inches long (5th instar). They’ve been known to defoliate ornamental trees in other areas, but we haven’t heard of this in S. California.  Let us know if you’ve seen this in S. California.  For more on larval behavior see reference 3, below.

After the 5th molting, the Mourning Cloak caterpillar pupates (metamorphoses into adult form). The caterpillar leaves the host plant to search out a safe place to form a chrysalis, often under an overhang, large branch or other protected site (see ref. 4 for photos).  After a 10-15 day development within the chrysalis, the adult emerges.  In warm areas, adults enter a hibernation-like state (estivation) in the hottest part of summer, allowing them to survive the heat. 

Mourning Cloaks are not long-distance migrants, although they may migrate locally in California, from lower elevation winter sites to higher elevation breeding sites [7].  Adults over-winter in protected sites like tree cavities, under loose bark, among dried leaves or other sheltered places.  They emerge from winter hibernation with the warm weather.

We hope you’ll look for Mourning Cloaks in your own neighborhood. You likely will find them this year.  Look for the larvae as well as adults, if you’re lucky enough to have the host plants.  And send your photos to iNaturalist (https://www.inaturalist.org/home).   We’re sure there’s a scientist interested in studying the yearly fluctuations in butterfly numbers.  Your pictures can help provide the data s/he needs to conduct their study.

Mourning Cloak (Nymphalis antiopa) : in garden

 

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  1. http://www.ukbutterflies.co.uk/species.php?species=antiopa
  2. https://en.wikipedia.org/wiki/Nymphalis_antiopa  
  3. http://www.naturenorth.com/spring/bug/mcloak/Fmcloak.html
  4. http://nathistoc.bio.uci.edu/lepidopt/nymph/mcloak.htm    
  5. http://www.desertusa.com/insects/mourning-cloaks.html
  6. http://www.projectnoah.org/spottings/10920101
  7. http://butterfly.ucdavis.edu/butterfly/Nymphalis/antiopa  

 

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We encourage your comments below.   If you have questions about the Mourning Cloak butterfly or other gardening topics you can e-mail us at :  mothernaturesbackyard10@gmail.com

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