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Saturday, February 8, 2020

Hardy Brushfoots

American Lady nectaring on Elbowbush
Winter is hardly a notable time for watching butterflies, except for those in the Nymphalidae family known as the brush-footed or brushfoots.  Most of these species are medium-sized to fairly large butterflies that hold their wings flat when resting and have a reduced pair of forelegs.  This group is also commonly called four-footed butterflies, because they are known to stand on only four legs while the reduced pair are held up against their mid-section or thorax. 

In some species, these shorter forelegs also have a brush-like set of soft hairs called setae, and it is unclear why these forelegs have become vestigial, or appearing to lose most of their ancestral function.  One theory is that these forelegs may be used to amplify the sense of smell (yes, many butterflies ‘taste’ with their feet!), while others believe they are used to improve signaling and communication between individuals of the same species, while standing on the other four.  The latter seems to be the leading theory so far, as that ability would prove most useful in terms of reproduction and the continuing overall health of the species.

More remarkably, brushfoots are experts at overwintering, or the process by which they pass through or wait out the winter season.  While many insects overwinter as eggs or pupae, brushfoots overwinter as adult butterflies.  They take cover in places such as building crevices, under loose bark, or beneath fallen leaves or other plant matter.  These places shield the brushfoots from the adverse conditions of winter, and their activity ceases until conditions become more favorable.  

Mexican Plum
Texas Redbud
On the occasional warm winter day in Central Texas, these butterflies often emerge to bask in the sun and feed on various nutritional sources such as tree sap, rotting fruit, or animal scat.  They are also found on early blooming native shrubs and trees, including Elbowbush (Forestiera pubescens), Mexican Plum (Prunus mexicana), and Texas Redbud (Cercis canadensis var. texensis), all of which are typically blooming in February.

A Red Admiral nectaring with its wings closed 
While many brushfoots are brightly colored on their upper sides, their undersides are largely dull and cryptic, mimicking dead leaves and bark, offering them additional protection in their chosen overwintering sites.  Examples of the most frequently encountered and easily recognizable brushfoots in our area include the Question Mark (Polygonia interrogationis), Red Admiral (Vanessa atalanta), Common Buckeye (Junonia coenia), and American Lady (Vanessa virginiensis).  

Question Mark
The Question Mark is fairly common in woodland openings, and is recognized by its deep orange wings spotted with brown and angled sharply at the edges.  Its cryptic underside is textured brown, resembling a dead leaf, and its hind wing is ‘punctuated’ by a curved silver line and dot also on the underside, which gives it its common name.  

A basking Red Admiral
Red Admirals are almost unmistakable, dark above with bright orange-red slashes and white dots on the outer part of the forewings, but intricately colored in mostly browns and blues below.  

A Common Buckeye warming in the winter sun
The Common Buckeye prefers open habitats, and can be identified by its overall golden brown color above, interrupted by large and striking multicolored eyespots.  

An American Lady resting on Elbowbush
Also preferring open or semi open habitats, American Ladies have an upper side with a mottled orange and brown pattern highlighted by white spots near the forewing tips, and the underside of the hind wings have two large eyespots in an olive background.  
The next time the weather is sunny and warmer, make a point to go outside and take a walk in the woods, a field or your garden, and see if you can find some of these hardy brushfoots!