Friday, November 28, 2014

Five hairstreaks of south Texas

Sweet face on a dusky blue groundstreak
Hairstreaks, of the subfamily Theclinae within the family Lycaenidae ("gossamer wings"), are small butterflies that are most diverse in the New World tropics [1]. I think they are highly underrated, as far as butterflies go. While they are certainly 'cute', telling them apart can be a challenge. Many of them are dainty gray butterflies with wing bands, eye-spots on their hindwings, and wispy tails.

I thought it might be instructive to go through key field markings. For this purpose, I searched through my back catalog and pulled images of five different species of hairstreak I've observed here in Texas. The subjects I've selected include three relatively similar-looking hairstreaks (the dusky blue groudstreak, the gray hairstreak, and the mallow scrub hairstreak) and two more distinctive hairstreaks (the great purple hairstreak and the silver banded hairstreak).

A gray hairstreak (Strymon melinus)
First, let's start with one of the most common and widespread hairstreaks in North America: the gray hairstreak. Larva tend to eat mallows and legumes, while adults are nectar generalists [2]. I would consider the gray hairstreak to be the "generic hairstreak", the hairstreak from which all others are differentiated. Note the relative cleanness and lack of clutter between the wing bands and wing edges. Also, remember the thickness, numbers, and placement of the orange markings on the hindwings. These are all traits that will vary from species to species.

Dusky blue groundstreak (Calycopis isobeon)
Now let's compare the gray hairstreak with the dusky blue groundstreak. This butterfly's larval food source matches its name ('groundstreak'): it's caterpillars feed on decaying leaf matter and other detritus [3]. At first glance these two hairstreaks look pretty similar. However, remember to check the eye-spots. The dusky has two well defined eye-spots outlined in red, versus the gray's one and a half. The dusky blue groundstreak has a third iridescent blue spot on the bottom edge of its hindwing, below the red and black eye-spots. This marking is totally missing in the gray hairstreak. The wing bands also differ- the dusky has obvious red outlining the post-medial band on its hindwings, and the thickness of this red outline is one of the field marks distinguishing it from its cousins. There's also provenance. The dusky blue groundstreak is only found in south Texas within the United States. If you anywhere but south Texas, then odds are it isn't a dusky blue groundstreak.

Mallow scrub hairstreak (Strymon istapa)
The mallow scrub hairstreak, which is actually in the same genus as the gray hairstreak, looks a bit different from the preceding two butterflies that I covered. When I saw this butterfly up in the canopy nectaring on Mexican olive (not pictured), I initially couldn't decide if it was a hairstreak or a tailed blue. I was better able to pick up on some of the identifying markers upon closer inspection.

Remember when I wrote about the uncluttered wings of the gray? The mallow scrub hairstreak is most definitely messy. There's a whole host of scribbles and bands in white and dark gray after the post-medial line. There's also minimal red on the eye-spots. Lastly, look at the front part of the hindwing and note the two dark gray spots. These two spots before the hindwing's band distinguish this hairstreak from all others. Like its con-generic the gray hairstreak, the mallow scrub hairstreak's caterpillars feed on mallows. This species is confined to the southern-most portions of the United States.

Another important thing to remember when identifying hairstreaks is that sometimes they don't have tails. The entire purpose of the eye-spotting and enticing tails on their hindwings is to encourage birds to take a nip there instead of other, more critical, areas. Many species of hairstreak even twitch and fidget their tails such that they resemble antennae.

Silver banded hairstreak (Chlorostrymon simaethis)
This silver banded hairstreak has seen better days. Either he's scrunched up, or something took a medium-sized chomp out of his right hindwing (he's scrunched up- ed.). The other side still seems to have its tail. Silver banded hairstreaks are another southern species. Their larvae are rather sly. Instead of feeding on leaves and exposing themselves to visual hunters, they hide inside the pods of balloon vines and eat the seeds [5]. This green hairstreak is pretty distinctive for a number of reasons. Its green coloration and straight silver bands are some of the easiest cues to pick up on in the field.

Great Purple Hairstreak (Altides halesus)
I'm going to end this post on the unmistakable great purple hairstreak. This butterfly has a wide distribution across southern North America. When I first saw this butterfly I was floored by its iridescent markings. The blue green markings on the edge of hindwings flashed in the sunlight whenever the butterfly re-arranged itself on the flower head. Its body is bright orange, and its wings are touched with bright blue. Their larvae eat mistletoe [6].

Obviously, this butterfly is quite distinct from most hairstreaks. However, the tells are still there. Like other hairstreaks, Great purples are petite with thin little tails, in contrast to the thick, chunkier tails on swallowtail butterflies. They also tend to sit with their wings folded, instead of spread to catch the sunlight.

In summary, many small butterflies with eye-spots and thread-like tails on their hindwings are in the Theclinae sub-family. After you have narrowed your search to this particular group, sorting through your options to get to species will probably require a combination of eye-spot characteristics,  wing band size and coloration, and location.  Good luck!

A silver-banded behind


Saturday, November 22, 2014

Palo Pinto and the Butterfly Hound

Clouds echoing the topography, Palo Pinto County
God help me, I've turned a red-blooded bird dog (my german shorthaired pointer) into a butterfly chasing hound. It wasn't planned. It just happened naturally. Ever since I adopted her, I've taken her with me on my invertebrate photo hunts. I strap her to my waist with a leash, leaving my hands free to snap away with my camera. My impressionable pup seems to have picked up on me stalking bees and butterflies with my lens. She's realized these flittery creatures are of some importance, and worthy of attention. Now it's a race to see who can reach the bug first- me with my camera or her with her snapping teeth.  Funny enough, she's somewhat indifferent to her ancestral prey. We've actually spooked coveys without her paying much mind, but butterflies- she just loses her little head. I suppose we end up with the dogs we deserve.

View from the mesa
My dog's enthusiasm for lepidoptery got us in trouble a few weeks ago when we were poking around Palo Pinto County, the home of a (relatively) soon-to-be-opened 5,000 acre state park. My dog Colby does not have what I would call "cactus-sense".  Time and again, running headlong after a butterfly (this time of year it's sulphurs, admirals, buckeyes, and southern dog-faces) she would face-plant into a prickly pear or pencil cactus. I'd pin her down, grab her little maw, and pull the spines out with the pliers on my leatherman. You'd think she'd learn to take more care, but it seems her joie de vivre simply cannot be dampened by something so insignificant as a spine between the eyes or a nopal hanging from her wet little nose.

Keeping a willful dog out of the opuntia was... tricky. 
Topo and satellite images of our trek.
Bringing my naive dog to cactus-country was just one of many poor decisions that accompanied my trip to explore this rugged landscape prior to its development as a state park. I was in search of a sheer canyon with unusual plants located in the southern section of the parcel, off a recently bull-dozed road, not yet added to maps of the area.

I should mention that I have a somewhat poor sense of direction. I am great at following trails and using maps and compasses, but if I rely on 'instinct', it generally ends poorly. I had thought to bring a borrowed GPS unit and printed out satellite photos, but somehow I forgot about the unmarked road leading more or less directly to my target. As a result, we ended up bushwhacking straight up and over a low mesa, through thick juniper and opuntia scrub, when we could've just gone around. I just about had a conniption fit up on top when it was cactus thickets in every direction. I was convinced I was going to blind my poor dog (or, rather, she would blind herself being an idiot), and I'd have to carry her back to the car and race off in search of an emergency vet.  Despite these complications, we did find what we were looking for. We ended up turning back at the cusp of the canyon because it was fringed in a wall of cactus, and I just couldn't justify blinding my dog for the sake of exploration.

View from near the road to the canyon
Despite our misadventures, I was very impressed with the landscape. It looked like a translation of my mental image for "Texas" from before I actually moved here. Low, flat topped mesas were edged in rocky drop-offs, and they were lightly covered in juniper and mesquite. It is hard to believe that something so rugged and western exists less than an hour and a half from green, treed Fort Worth. It was a world away from the hackberry and pecan groves. I could see going into full-hermit mode out there. I'm a real sucker for rocks and spare landscapes.

Migrating sand hill cranes passed overhead
Once we reached the peak of our ill-advised mesa scaling adventure, we had a moment of peace. I could see for miles down the valley, a valley that raptors funnel through in their fall migration. I stopped and ate an orange and Colby huffed quietly. Then I heard a familiar gurgling trill from overhead: sand hill cranes! They were using the same flyway on their migration south to their coastal wintering grounds. I'm not sure Colby appreciated it, but I got a lot of joy from hearing the cranes. Seeing them pass through provides something of a thread linking my year in Nebraska with my time here in Texas. I'd like to return to this undeveloped landscape to see it change with the seasons, though if I bring Colby we'll stick to the roads.

Dog tired. (Hah!)

Thursday, November 13, 2014

Three polyphenic butterflies

This question mark hasn't given up on summer. (11/2/2014, Mission TX)
In an organism that is seasonally polyphenic, also termed seasonally polymorphic, the same genetic code produces different physical traits in response to environmental conditions. In butterflies this is quite common, and it is often expressed as "summer" and "winter"/"dry season" morphs. Day length and temperature seem to trigger these changes. Butterflies are most sensitive to these seasonal cues while they pupate, and they only get to choose their morph once (see comments).

Some researchers believe that polyphenism evolved as a solution to differing needs for camouflage and thermoregulation in summer vs. winter. Perhaps summer butterflies survive better on fresh green leaves in bright coats, while fall butterflies are more comfortable with darker coloration that allows them to soak up the weak winter sun. Fall butterflies also tend to live much longer-- some late-emergent butterflies hibernate for 9 months before reproducing, instead of the brief flight window and immediate reproduction of their summer kin.

Dainty sulphur. (11/8/14, Palo Pinto Co. TX)
I've encountered at least three polyphenic butterflies in the past couple weeks. Interestingly, these three butterflies couldn't agree on the season. Two were plainly marked for winter, while one insisted on hanging onto summer.

The question mark's dark morph is its summer form. In the winter, the hind wings lighten. Question marks don't typically nectar on flowers-- like the hackberry emperor, they prefer to feed on dung and rotten fruit. That's the reason you see the question mark perched on a log in the picture above- someone had smeared the log with bait. You'll notice s/he shares the perch with flies.

Another pic of the dainty sulphur
For the dainty sulphur, the summer morph is paler with more yellow markings, while the winter morph has a mostly sooty coloration, especially on its hind wings. Dainty sulphurs are the smallest member of their family found in North America.

In white peacocks, the winter morph is larger and whiter than those which emerge in summertime. White peacock males are notable for a behavior that is somewhat unusual in the butterfly family. They defend patches of their larval host plant in hopes of monopolizing any passing females. These harmless insects perch in their small territories and engage rivals in aerial duels. I'm not sure how a 'winner' is determined. Each participant is essentially incapable of harming the other, unless it is by exhaustion.

The seasonally confused question mark looked pretty fresh, not at all like some holdover from longer days and warmer weather. I wonder if he will suffer for his poor judgement? Perhaps he pupated during  a warm snap, confusing his cues. The verdict of the dainty sulphur and white peacock, and the arrival of an arctic front, tend to suggest that cooler weather is here to stay, at least for a little while.

White peacock (11/2/2014, Mission TX)

Wiklund, C., & Tullberg, B. S. (2004). Seasonal polyphenism and leaf mimicry in the comma butterfly. Animal Behaviour68(3), 621-627.

Lederhouse, R. C., Codella, S. G., Grossmueller, D. W., & Maccarone, A. D. (1992). Host plant-based territoriality in the white peacock butterfly, Anartia jatrophae (Lepidoptera: Nymphalidae). Journal of insect behavior5(6), 721-728.

Nylin, S. (2013). Induction of diapause and seasonal morphs in butterflies and other insects: knowns, unknowns and the challenge of integration. Physiological entomology38(2), 96-104.

Karlsson, B., Stjernholm, F., & Wiklund, C. (2008). Test of a developmental trade‐off in a polyphenic butterfly: direct development favours reproductive output. Functional ecology22(1), 121-126.

Sunday, November 9, 2014

Tropicalia at the Texas Butterfly Festival 2014

The red-bordered pixie, a tropical butterfly in the metalmark family. Unique to So. TX within the US.
I saw so many 'lifers' at this year's Texas Butterfly Festival in Mission, I've honestly been putting off writing about it. It's such a huge bite to take. Some butterflies were rare, some were deceptively common on site, and others were overwhelmingly abundant. I've decided to break my sightings down into more easily digested chunks. Because many of the butterflies I saw are limited to the subtropical regions of the United States and farther south, I'm going to focus on those species today.

Zebra heliconian, of the tropical longwing family 
I was fortunate enough to spot a number of the more distinctive members of the local butterfly community. I think I most enjoyed finding the pixies and heliconians. These are two of the 'flag-ship' butterflies of the Lower Rio Grande Valley (LRGV). There they were- and in profusion. I also saw a Julia heliconian flit past, but sadly I couldn't get a picture.

Zebra and Julia heliconians are in the "longwing" family. These butterflies all feed on passionflower as larvae. The gulf fritillary is one of the more widespread representatives of this group. Gulf fritillaries were actually quite common on site-- the daft creatures were still reproducing. I even found a caterpillar climbing up a plumbago plant looking for a place to pupate. Gulf fritillaries perform a migration of sorts. They cannot survive freezing at any lifestage, so every year they must recolonize their entire northern range. The University of Florida's entomology page claims that the adults move south over the winter. For all I know the butterflies we see north of the freeze line are representatives of a giant population sink.

I'm pleased to have finally captured the full life cycle. First comes a passionflower, then a funky caterpillar, and then 'voila', a gulf fritillary.

How to make gulf fritillaries
My other tropical finds included the soldier, white peacock, the surprisingly lovely brown longtail, the sickle-winged skipper, (possibly) a silver-banded hairstreak, among others. Pictures and the full list after the jump.

Next week: the finer points of hairstreak ID.

Friday, November 7, 2014

A new savanna outside College Station, TX

This savanna made possible by heavy equipment.
College Station has a new oak savanna, thanks to a creative restoration effort by a local landowner and a TPWD biologist. Originally, the landowner had approached TPWD with the thought of putting his land back to native grasses. He was getting older, and he wanted his holdings to look like native prairie again. Most land in the area is dominated by the commonly over-seeded nonnatives: bahia grass, bermuda grass, johnson grass, and various old-world bluestems.

Great purple hairstreak nectaring on old frostweed
On this particular site, however, the problem was thick brush, especially yaupon holly, choking out the native post-oak's understory like a green wall. Inspired by the compensation offered from the frackers who owned the mineral rights and were coming in to build a new pad on-site, the landowner instead negotiated for hours with a bulldozer. After clearing the brush he over-seeded with the native grasses recommended by TPWD.

The site looked great, exceptionally so for a year '0' restoration. Many of the seeded native grasses have established, as have some pioneering flowering plants. Beautyberry and pokeweed were most abundant. I also spotted a few tendrils of maypop, frostweed, smartweed, and some other species.

closer: great purple hairstreak
Frostweed (Verbesina virginica) is a wonderful plant, an important late-season butterfly resource with a unique attribute: during the first freeze, its sap is extruded through the stem where it solidifies into curling 'ice sculptures', similar in appearance to the icy frost flowers that burst up through the ground in colder climates.

A gorgeous great purple hairstreak was investigating the few remaining blossoms on a tall frostweed in the center of the savanna. He (?) was shimmying the tails on his hindwings enticingly- evidently a behavioral adaptation to encourage birds to take a nip there instead of places where they could cause real damage. Interestingly, great purple hairstreak larvae eat only broad-leaved mistletoe. I didn't think to examine the treetops for these arboreal parasitic plants, but I can imagine that a savanna with an understory of rich nectar sources and an overstory hosting their larval food plant would be a good place to make a living as a butterfly.

I think most people find savannas quite aesthetically pleasing, and I hope this site stays lovely, propelled forward by a solid start.

Beautyberry lit by a patch of sun in the understory
Lady's tresses, Spiranthes spp.
The landowner's other sites were not so easy to restore. Simply making room for other plants in a matrix of the aggressive non-natives is no small undertaking. Repeat applications of glyphosate or imazapyr are often needed to even make a dent in the exotic grasses. This sort of broadcast chemical application makes my little heart sad, but sometimes it is a necessary evil. Notably, in the case of this landowner's other holdings, applications of herbicides had successfully suppressed the nonnative grasses and released the native grasses that had been holding out all along. I do still worry about the broadleaf plant community under these circumstances. However, a lone lady's tresses orchid had managed to put up a bloom in the middle of a sprayed patch. If an orchid, a representative of a characteristically delicate family, can push through, then maybe there is still hope for the others.

Sunday, November 2, 2014

The three milkweed butterflies of the United States

Queens (Danaus gilippus) were... not uncommon.
I have had a wonderful time exploring central and south Texas over the past few weeks. After attending the Texas Butterfly Festival, I feel it is appropriate to write a brief butterfly-centric post. I see more of the ilk in my future-- I saw so many new butterflies, including tropical species! At any rate, it's been a blast.

The controversial non-native tropical milkweed
(Asclepias curassavica). The leaves are evergreen. 
One of the highlights of my travels has been to finally see a soldier butterfly (Danaus eresimus). Soldier butterflies, like monarchs and queens, use milkweed exclusively as their larval host plant. Unlike monarchs and queens, their range barely extends into the United States. The subtropical tips of of south Texas and Florida are the only places you can really hope to find them. I was fortunate enough to see all three milkweed butterflies in the same garden on the same day (!) in Mission, Texas at the National Butterfly Center. They were really loving the betony-leaf mistflower (Conoclinium betonicifolium)

This is the best time to see butterflies down in south Texas' Rio Grande Valley. This area hits its peak butterfly density in October and November. The Rio Grande Valley is special. It marks the northern-most extent of number of largely tropical butterflies- a few of which I saw and will cover in a future post.

The monarch butterfly
Because the queens, soldiers, and monarchs (Danaus plexippus) are all very similar in appearance, I thought it would be useful to include pictures of all three to compare the various field markings. First:  the classic monarch butterfly. Flashy and readily seen, though threatened by habitat loss in much of North America, this species can be found from Texas to Canada. They are the only milkweed butterfly with a confirmed long-distance migration, and they are much larger than both the queens and soldiers. Their size and bright orange coloration make them pretty easy to distinguish. Also, their veins are a high-contrast black instead of brown or undifferentiated in color from the wing.

Mating queens
Queen butterflies (Danaus gilippus) are smaller, more brown than orange, and they don't have the same contrasting black venation visible on their dorsal (topside) as  monarchs. They also have two lines of white dots on the dorsal side of their forewing (leading wing), versus the single line observed in soldiers. Their overall color is darker and duller. Queens are quite common in the parts of south Texas I visited- they are much more frequently found than monarchs along the coast here. They are something of a southwestern species.

Soldier butterflies are definitely the most uncommon of the three milkweed-feeders. Sometimes they stray into southern Arizona, but they primarily stick to the subtropical areas of the United States. They are the veritable four-leaf clover in the field. In addition to being distinguished from queens by their single (instead of double) line of white dots on the forewing, they also have a dusky dark patch in the middle of their hindwing. Overall, they are a rich shade of brown.

The uncommon, hard to spot soldier butterfly

So that's it! The three North American milkweed butterflies. Stay tuned for a more lengthy update on the other unusual species I found down on the border...