Where Are All Those Butterflies Going?

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Monarch butterfly

Most people are familiar with the famous migratory flight of the monarch butterfly (Danaus plexippus).  These resilient colorful lepidopterans are a familiar sight twice a year in the state of Texas as they make the arduous journey to their summer fields of Canada and then back to Mexico in the fall.  With their bright “Halloween” colors of orange and black, coupled by their large size, they are one of our more conspicuous species of migratory butterfly.  But Texas holds several additional species less well known that also make annual or biannual trips to warmer haunts with the advent of autumn.  With the gradual cooling of days, a host of different species can be seen flitting over open areas on sunny mornings, some in a leisurely fashion and others at a determined rapid pace that seems to reflect the ever-impatient rabbit borne of the Lewis Carroll novel, Through The Looking Glass.

One of these is the Queen butterfly (Danaus gilippus), a close relative and mimic of the monarch.  Although slightly smaller and of darker coloration, the pattern is quite similar, enough so that very few Queen butterflies fall victims to avian predation.  Birds seem to know well and resist the distasteful toxins of the monarch, which are absorbed into their bodies during their larval stages through the toxic milkweed they consume, and the color and pattern similarities between these two species offer the queen butterfly a VIP pass as it slowly wings its way across fields and abandoned lots, flying low to the ground and seeming to stop to visit every flower.

These butterflies are principally subtropical in nature, and seldom fly far enough north into the United States to constitute a large migration pattern, but they are a common sight in the American southwest April through October.  The rest of the time is spent south of the border, and in the early fall months this is one of the most common species seen in the lower Rio Grande Valley as large numbers make their way to greener winter pastures.

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Gulf fritillary

Another very common and dazzlingly beautiful species that migrates in the state is the Gulf fritillary (Agraulis vanillae) This fast-paced flier is mad about passion vine, its host food plant, and thus is a common visitor to flower gardens where this plant is found.  Bright orange on top and brown and silver beneath, they are easily distinguishable from other species.  Gulf fritillaries are not true fritillary butterflies, but rather members of the genus of subtropical butterflies known as heliconians.

One of our most prolific mass-migrators is the American snout butterfly (Libytheana carinenta).  Inconspicuous when at rest on a twig, after being closely approached they burst forth suddenly in an explosion of orange.  On any given year in the fall snout butterflies can be seen winging their way south, usually in dozens but occasionally by the thousands.

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Top L: Snout butterfly; Top R: Red admiral; Bottom L: Painted lady; Bottom R: Cloudless sulphur

Two other familiar species of butterflies belong to the family known as ‘brush foots’.  The red admiral (Vanessa atalanta) is a handsome species, chocolate brown with bright bars of scarlet on the fore and hind wings and white dots or patches on the wingtips.  This species normally overwinters beneath rock overhangs or in dense brush, and during years of high population density large numbers of adults that have overwintered in warmer climates break northward for higher and cooler elevations.

The painted lady (Vanessa cardui) is a cosmopolitan species that takes this same migration pattern to a global scale.  Fast and erratic fliers, these noticeable insects with blue and brown eyespots on the underside of the hindwings and the telltale pink slash of color beneath the forewings are one our most common species, and migratory groups traveling north from their winter haunts below the equator can number in the millions.

A vibrant and easily identified migrator is the cloudless sulphur (Phoebis sennae).  With its bright highlighter-yellow coloration and zippy, darting flight pattern its presence in a park or backyard is hard to miss.  In late summer large numbers of these butterflies fly northward high in the air.  Their determination is in direct contrast to their springtime behavior, where they can often be approached quite closely as they visit bright flowers or mud puddles.

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Painted lady

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Painted lady, showing undersides of wings

One of our smallest migratory species is the fiery skipper (Hylephila phyleus).  Skippers are a strange paradox in the lepidopteran world, and appear to be a weird mixture of both moth and butterfly.  They are diurnal, but possess the general stout body structure common to moths.  Of the confusing array of similarly marked species of skipper that flit about gardens, roadsides, and open fields wherever flowers abound in our state, the fiery is an example of a specific migrator.  This species, like many types of lepidoptera, is sexually dimorphic, meaning the sexes can be distinguished visibly by physical coloration, pattern, or other characteristics.  Males are clothed in the brilliant yellow-orange that gives the species its common name, and females are, as is often the case in nature, more somberly hued.  Each September large numbers of fiery skippers can be seen in north Texas as they dance among the goldenrod and dandelions at road’s edge.

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Fiery skippers, male (top) and female (below)

Butterflies, like birds, are well known for their migratory habits, but few think of moths migrating.  However, one of the most epic and amazing migration stories comes from the natural history of the black witch moth (Ascalapha odorata).  Chiefly a subtropical species, the black witch is a truly impressive insect.  Called Mariposa de la muerte or “butterfly of death” in its native Mexico, these bat-like giants with wingspans of up to seven inches fly north across the border in the month of June, their departure coinciding with the southwest’s monsoon season.  During this time, and on through the fall as late as October they can be common visitors to lights across the state.  Their adult stage, which only lasts a month or less, leaves them no opportunity for actual overwintering sites, but the species appears to make a general course across the heartland from Texas to North Dakota, with wandering strays appearing in such unlikely northern places as New York and even Manitoba, Canada.  Unlike butterflies, and in true noctuid fashion, the black witch migrates at night.  One interesting and unsolved mystery of their travels involves huge “fallouts” of black witches dropping to the ground in the middle of tropical storms, where their bodies sometimes litter the sidewalks of coastal port towns along the Gulf of Mexico.  Apparently the moths travel in the eye of hurricanes, a phenomenon whose exact reasons are still unknown.

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Black witch moth

The arrival of fall brings a change of pace to our lives in Texas, bringing cooler temperatures, shorter days, and the beautiful adornment of native hardwoods with cloaks of multi-colored foliage.  It also brings about an influx of butterfly activity, so the next time you step outside and notice an unusual number of butterflies on the wing, stop to wish them well.  They just may have a long way to go.

References:

Brock, J.P. & K. Kaufman. 2003. Kaufman Field Guide to Butterflies of North America. Houghton-Mifflin

The Black Witch Moth: Its Natural & Cultural History – www.texasento.net/witch.htm

The Eastern Yellow-Bellied Racer and the Jump to Light Speed

There was once a time when I could chase down an eastern yellow-bellied racer. Well, if it was on a flat surface … maybe if I had a head start. Probably not now, unless my head start was that I was allowed to grab it before it saw me. These snakes are not called “racers” for nothing.

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Eastern yellow-bellied racer

They can cruise around on a hot summer day, their big eyes alert to any movement, watching for a grasshopper or lizard to spring into action, and ready to give chase. When they do flush some unfortunate prey animal, they are unrelenting in pursuit. When a big grasshopper lands and freezes, the snake may have to search until it again makes the insect jump, and at that point the chase resumes. Having no venom and no ability to wrap and constrict, the racer simply swallows its prey or maybe pins it on the ground with a section of its body while swallowing. Racers can eat animals as large as a mouse or medium-sized frog, relying on the rows of sharp, recurved teeth and strong jaws to overcome the struggles of its prey.

Many years ago, my family moved to Fort Worth and my knowledge of reptiles and amphibians expanded from days spent hanging out with museum staff and reading books. At the end of the summer, I would occasionally find a little spotted snake around the yard. Their pretty yellow bellies were speckled with rust-colored spots, and as I held them their large eyes looked alert, and their jet-black tongues tested the air. Around the same time, a group of us kids found a medium-sized snake stretched along a branch within a shrub in a neighbor’s yard. It sat motionless, watching us, and I recall it being a sort of olive greenish color. I was puzzled about this snake’s identity but later figured out that it was what some people called a “blue racer,” but down here in Texas it was a different form called the eastern yellow-bellied racer.  With further study, I discovered that the little spotted snakes I sometimes found at the end of summer were actually hatchlings of that same species. Over the course of a couple of years, the spots would fade and the snake would be brownish or olive or grayish-blue on top, and yellow underneath.

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A juvenile eastern yellow-bellied racer, probably in its second year, still showing the spotted pattern.

Occasionally I would find one in the field, sometimes as a serpentine blur disappearing in the grass. Other times I might find one under a board or a rock, and if I grabbed quickly, I might get a close look at this muscular coil of pure energy. When grabbed, that same energy is directed toward thrashing and biting, and the poor snake may injure itself if not supported properly. The bites are annoying but not particularly painful, and they seem to come out of nowhere as the snake thrashes around to a new vantage point. However, when gently supported and not harmed, the snake may settle down, after a fashion, continually testing the air with that black tongue and watching its captor like a hawk. Drawing the animal closer, for a detailed look, often results in a strike aimed at the person’s face. Loosening the grip a little too much results in a sudden attempt to break free, as if the racer was waiting for just this opportunity.

Part of the racer’s reputation as a snake that can make the jump to “light speed” is its ability to navigate through brush and around rocks without slowing. Its top speed is actually a little slower that a person could run on a track, but when seen, these snakes are often around rocky outcrops, fallen logs, or tangles of undergrowth, none of which cause the snake to slow down. Imagine the speed with which this reptile processes the visual images coming at it, like a fighter pilot flying low over the landscape, dodging left and right but keeping right on going!

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Eastern yellow-bellied racer

Eastern yellow-bellied racers make use of a fairly large “home range,” or area within which it hunts, rests, finds water, and so on. In their book, Texas Snakes, Werler & Dixon cite research done in Kansas showing that racers may use about 25 acres as a home range. Within that area, the individual snake may be familiar with refuges such as a particular abandoned burrow or crevice under the rocks, and where the best pools in a little creek may be. These racers prefer open areas such as patches of prairie or savannah, and they may hang around near the edge of a woodland.

Texas has a four other forms or subspecies of racer. The buttermilk racer lives in parts of east Texas, and has the same overall bluish-gray to olive coloration but is speckled here and there with small globs and specks of white. The tan racer, found around the Big Thicket, uses forest habitat much more than the other racers, and is a uniform tan color above and pale whitish below. Along the southern Texas coast, the Mexican racer zips along through the thorn scrub. And at the northeastern corner of the state, the southern black racer is found in several counties.

On a cool, overcast day in March, 2012, I found a young eastern yellow-bellied racer under a big rock in Wise County. I was out with Clint and his wife, and we thought we might get an early start on field herping that year. Sure enough, we did find several things, but everything was under cover, since March in north Texas may turn unpredictably from sunny and fairly warm to rainy and cool. When I turned the rock over, the young racer was too cool to dart off. Oh, the disadvantages of being an ectotherm! Being cold-blooded means that if you hang out in a cold place, you are cold, too. The engines that drive all that nervous, alert activity depend on warmth, and if you’re a reptile you cannot generate your own heat. The little snake sat while I recorded it on video, tongue-flicking and moving slowly. It even flattened its neck vertically a little at one point, in a threatening display meant to make it look bigger. To see the video, click here.

In the summer, being an ectotherm would be a big advantage for the reptile. Us endotherms have to take in lots of nutrients so that our metabolic engines can constantly generate heat. Snakes are “solar-powered,” directly or indirectly, making use of sunlight or a sun-warmed environment to get up to speed. As a result, they do not have to eat as often. But on this day, at the end of winter, the little racer was slow-moving and vulnerable. After I got all the photos I wanted, I let her return to the shelter of the rock and wait for a warmer day.

If you find one, admire whatever glimpse you get of this snake and let it go. That three-feet or so of nimble hyperactivity will just make you sprain your ankle or get a face full of cactus if you chase it. Or maybe, if you’re lucky, you will find one under sheets of tin, or boards, or under a rock on a cool day when light speed is not an option. They are beautiful, graceful animals!

Scorpions of the Chihuahuan Desert

Roll over any random rock of fair size in the American southwest and before long you’re bound to come face to face with one of nature’s most efficient, feared, loathed, and misunderstood creatures.  Though of comparatively diminutive size and reclusive habit, the scorpion has long been a symbol of the southwest, of danger and formidability.  Armed with an ironclad exoskeleton, a pair of scissor-like pincers and a long, segmented tail that ends in a sharp, curved meathook-like sting capable of delivering a powerful dose of venom to predator and prey alike, it is no wonder man has long held the lowly scorpion with a mixture of distanced respect and general disdain.  Often seen as vermin or at best an outdoor hazard to be constantly on the alert for whenever hiking, camping, or just walking around barefoot at night, residents of the southwestern United States learn quickly not to tread on them, and individuals once stung are usually twice shy.  Shoes are shaken out with force, bedsheets checked thoroughly before turning in for the night.  As my wife’s grandfather once commented, “If you ever feel strong just try to hold down a scorpion with your thumb.”

As an inquisitive child growing up in the western cross timbers, I quickly became acquainted with the local flavor of scorpion, Centruroides vittatus, better known as the striped bark scorpion.  In fact, one of my earliest memories was that of a neighborhood friend and I discovering one in my back yard.  I mentioned this to my mother years later and she told me I must have a very good memory, as we moved from that house before I turned five.  (I prefer to think of my memory bank as being more selective than vivid.)

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Striped bark scorpion

As fate would have it, our move deposited us on the edge of the Wilson Prairie in western Wise county, which to a budding young naturalist served as a personal classroom.  And it was a hard lesson learned the day I rolled over a log and unknowingly placed my hand on a bark scorpion taking a siesta on the other side.  One moment I was struggling to free the log from its place in the ground and the next I was howling in pain as my thumb was set ablaze by some new invisible form of fire.

Several years (and several more stings) later, I began to make summer pilgrimages to the Chihuahuan desert.  By this time my love of all things venomous  had expanded to include spiders, centipedes, and snakes.  It was there that I was introduced to an entirely new and different crop of scorpions, and my knowledge and appreciation of these fascinating arachnids began to evolve.  The now-familiar bark scorpion, inarguably the most common species in the state, was still present, although these desert variants were marked somewhat lighter.  A friend and I found several examples of these in the creek drainage between Terlingua and Lajitas while hunting lizards among the catclaw (a much more dangerous activity).  Centruroides vittatus is very fond of wooded areas, where it finds suitable shelter in piles of dead fall as well as behind the loose bark of old oak trees, hence the common name.  But here in the desert, oak trees are a rare sight indeed, and so this species (as well as most of the others that call this arid environ home) utilizes the cool, moisture-retentive spaces beneath and between rocks.

The next genus I came across in my adventures to the Big Bend area were the Diplocentrus scorpions.  Larger, darker, with thick pincers and a more irascible disposition, these shiny black arthropods were common beneath rocks in the Christmas Mountains in southern Brewster county.  Before long I identified them as Diplocentrus lindo.  Although their stings are very mild, they make up for this with a strong pinch not unlike that of a small crab.

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Diplocentrus lindo

I’ll never forget my first Diplocentrus whitei.  While shining rock cuts for snakes on highway 118 between Terlingua and Alpine my beam fell upon an enormous shiny black scorpion protruding from a dime size hole that had been excavated from the side of the cut.  Only its pincers were exposed, but they were immense!  The creature immediately scuttled back into its subterranean shelter, hiding from this foreign intrusive artificial light that had so suddenly and rudely interrupted its night.  Dismayed at not being able to extract and observe such an uncommonly large and impressive scorpion as this one, and yet not willing to destroy its home and habitat just to get a peek at it, I devoted the remainder of the night to finding one out in the open.  Several cuts later and I got my chance.  This one had no place to hide, but it did have a plan B, which it executed with all the vigor and vim of a cornered mountain lion.  The oversized pincers raised, clicking together audibly as it snipped at the air.  The arched tail followed between snips, thrusting forward, seeking flesh.  I had to admire its insane courage, and was grateful for the fact that I was much larger than it.  After a snapshot or two I left it there to calm down and resume its nocturnal wanderings.  Diplocentrus whitei is unique among Texas scorpions in that it occurs north of Mexico only in the Big Bend region.  It is also the state’s largest scorpion, with adults achieving maximum lengths of well over two inches.

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Diplocentrus whitei

Diplocentrus lindo and D. whitei are the only two members of the genus occurring north of the Rio Grande, but another group of scorpions, Vaejovis, are among the most diverse and numerous.  Generally smaller and paler, with thinner pincers, tails, and bodies, this huge genus of scorpions can be very common in the Chihuahuan desert.  In fact, my first Vaejovis waueri was found in my motel room hanging out on the floor by the lamp stand on a routine trip to the ice chest.  An olive green beauty with black pincers and dark brown stripes along the abdomen, it is one of our more colorful native scorpions.

Identifying other members of this genus to species can be tricky, as there are quite a few, including the quick and aggressive V. intermedius, the straw yellow V. crassimanus, and the ghostly pale V. russelliVaejovis coahuilae, perhaps the most common species, always turns up around the blacklight I set up to attract night flying insects at the Longhorn Ranch motel north of Study Butte, eager to take advantage of the free buffet.

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Scorpions of genera Vaejovis (top) and Paruroctonus (bottom)

A fourth genus, Paruroctonus, is the largest genus of scorpions in the U.S., although the Chihuahuan desert boasts only four species, being far outnumbered here by Vaejovis.  These typically resemble bark scorpions in appearance, although they are of more pallid coloration.  P. gracilior and P. utahensis are both typical species, and fairly common, although the genus includes such rarities as P. boquillas (named after Boquillas Canyon in Big Bend National Park, where the type specimen was found), to P. williamsi, of which few specimens are known.

The genus Pseudoroctonus includes only a single native species, and this is P. reddelli, the Texas cave scorpion.  Initially described as Vaejovis reddelli, it is a common and widespread species found only in and around caves in central and western Texas.  Specimens of this reddish brown to black hued species make their homes inside the caves, and field research has shown that those attain greater lengths than the ones living around the cave mouths.  Habitat specific, they are also highly specialized feeders, with their diets consisting almost solely of cave crickets.

Scorpions are unique and interesting members of our native fauna in the Lone Star state, and the complex details of their lives include such intriguing aspects as mating “dance” rituals, variable venom compounds, and the fact that their exoskeletons possess a combination of chemicals (including beta carboline) that cause them to glow yellow or turquoise under ultraviolet light.  Far from being hideous, revolting, deadly, or a cause for panic and alarm, they are true biological wonders that fill an important niche in our natural world.  They are important consumers of insects, miniature armored tanks well-enough adapted for survival that they were around long before the dinosaurs, survived the Ice Age, and continue to thrive in the ever-encroaching presence of man.  Their diversity and very presence help make the desert what it is, a wonderful, mysterious landscape full of life, provided one is inclined to turn the occasional stone and peer for a moment into their secret world.

Alpine, Texas, September 8, 2016

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A Trans-Pecos sunset

I am a long distance admirer of Alpine and other communities in the Trans-Pecos, and in short visits during many trips to the Big Bend region, I have built up an idealized perception of these places as friendly, easygoing refuges from the rest of the world. Today, a young girl in Alpine took her own life after shooting another student. The idea of a school shooting in Alpine seemed as impossible as the notion of a hate crime in paradise. It happens all too often in those other places in America, but not in the Trans-Pecos. Not in that beloved place where people live alongside nature and (mostly) do not wreck it. Not in that place where human evil does not dominate.

While Clint and I try not to be naïve, this idealized view was reinforced in a trip just last weekend to the Chinati Hot Springs. We met a warm and generous family from Alpine. As we started talking about what we were doing, it became clear that Symantha was fascinated with snakes and other wildlife, and we all became instant friends. There in the communal kitchen at the hot springs, we shared stories and they shared dinner with us. It was the kind of night we long for and seem to have lost – eating and laughing, walking out onto the porch to stare up into the stars or find unusual insects, miles out in the beautiful Chihuahuan Desert. If Alpine was like these people, it truly must be a charmed place, a little bit this side of heaven.

And these communities are scattered across the most beautiful country we know. The fact that most of the vegetation has thorns and many of the snakes are venomous does not take away from its wonder. On a clear night, you stare up into infinity into which the creator has thrown a double handful of diamonds. You can stand on a mountain and look out across a landscape without stores and freeways, where people are present in small numbers, not a teeming hive. It is easier to see our fellow humans as individual people, not an overwhelming hoarde. And when you want to see no one, that’s easy to do. The Trans-Pecos is one of our favorite places on the planet.

With that in mind, today’s violence feels like an assault. It must be much worse for those directly affected. We will never know the terrible impact of the girl’s death on her family, or how the gunshots that others suffered will haunt them. And we don’t fully appreciate what the other students may experience in the coming weeks, wondering if their school can ever feel safe again. How will Symantha feel, going back to school? But for those of us who just get to visit occasionally, who love the land, the wildlife, and the people we have met there, it feels like a nightmare intruding into a dream, or poison seeping into a precious refuge.