I am sitting on the veranda of the Darling Ranch house as I write this, watching the sun go down over the massive old live oak tree, with our first day in the Rio Grande Valley behind us. A front blew in overnight, blanketing the sky with grey cloud cover until after noon, but we decided to make a go of it anyway and get out into the field to see what we could find. After hitting a taqueria for breakfast (and chasing a huge black witch moth across the parking lot with no success) we headed for La Sal Vieja, a national wildlife refuge consisting of two lakes northwest of the town of Raymondville.
La Sal Vieja is so named due to the salinity of the lakes and the subsequent salt deposits that were once collected first by the Native Americans and later by the Spanish conquistadors. But with good old NaCl now available by the bag at any number of grocery stores and no longer a precious commodity, we focused our interests on the birds, bugs, and plant life.
Aside from the salt deposits, La Sal Vieja is not unlike many of the other public land areas that dot the thornscrub in the lower Rio Grande Valley. A narrow sandy trail winds through thick stands of mixed vegetation, with the predominate mesquite appearing alongside Baccharis, Junco, and Ebony blackbead. In the shade of these hardy species grow prickly pear in abundance, as well as a host of other succulents, grasses, and legumes. The ending result is an almost impenetrable mass of close-growing, often thorny vegetation, collectively refered to as the thorn scrub.
While it may not be HOA approved landscaping, this verdant mixture of growth is home sweet home for a plethora of mammals, birds, reptiles, amphibians, and invertebrates, the latter of which I was trying to get to fall into my canvas sweep net by dragging it through the high grass and shrubbery at trailside. Almost immediately this brought me into close contact with a beautiful jewel beetle of the genus Acmaeodera. Commonly referred to as “black and yellow buprestids” due to their similar appearance among species, these bullet-shaped borers are fond of yellow flowers, where they both blend in superbly well and mimic similarly-marked bees and wasps. This was a species I had never before seen in the field, but its atypical pattern of yellow margins on a black background with coral pink elytral blotches identified it as Acmaeodera flavomarginata.
As a self-described buprestophile, I was ecstatic to break the ice with such a specimen. At the time it seemed like a rare find, although I would later find this species in relative abundance at La Sal de Rey. But for now, it was fresh and new and provided me with just the boost of energy I needed to keep me going along the trail, bum leg be damned. Still, the going was slow, but it gave me the opportunity to observe things at my leisure instead of the usual high-speed burn I insist on maintaining when both legs are functioning at full capacity. But the slowed pace soon payed off in the form of two additional species of Acmaeodera, as well as a host of other great stuff of the six and eight-legged kind. The buprestids were being drawn to a low-growing, purple-flowered plant I later identified (hopefully accurately) as blue mistflower. It grew abundantly along the trailside, and in spite of the adverse weather (buprestids seem to prefer hot, sunny days) produced several dozen specimens of Acmaeodera haemorrhoa and A. scalaris.
Acmaeodera scalaris (above) & A. haemorrhoa (below)
All Acmaeodera aside, the sweeps produced their fair share of notable arthropods as well. Queen butterflies, those southward-migrating monarch mimics of slightly darker complexion, were present both in their adult phase in the air and their larval phase in the weeds. Their mimicry even bleeds over into the caterpillars, with the larvae closely resembling that of their more well-known close cousins. Like the monarch, the queen is toxic to predators in all stages of its life cycle.
Another interesting find that turned up in the sweep net was a cardinal jumping spider, a brilliantly-marked species of the large genus Phidippus, which includes the familiar black and white jumper that often makes its way into peoples’ houses. This one was stunningly beautiful, and in spite of its alert nervousness we both managed to snag a few decent close-ups before returning it to the high grass.
A few species of insects were in ludicrous abundance, with the presence of one being comparatively benign to that of the other. Geometer moth caterpillars (better known as inchworms) covered the trails, grasses, and anything in between. They seemed especially fond of the ebony blackbead trees, where a single rap from my cane into the basket of the sweep net would produce a hundred or more of them. A close inspection of these trees revealed dozens of specimens dangling from the branches by silken threads like weird ornaments, giving the trees the appearance of some strangely decorated Christmas tree.
While abundant in staggering numbers, the geometer moths paled in comparison to the legions of tiny, bothersome gnats that flocked to our eyes, ears, and noses. Resistant to Deet and unbelievably persistent, they were a constant nuisance from trail’s head to end. In fact, it was a sudden increase in their numbers that eventually led us to turn around and head back to the car. I was glad we did, for no sooner had we doubled back than I spied a pair of long, waving black antennae amidst the jade greenery of a small bush. These belonged to none other than Liconotus flavocinctus, a handsomely marked longhorn beetle I had previously only known from online field guides.
Another find worth mentioning, found on the same plant, was a land snail, later identified on inaturalist as the striped rabdotus. My son is into snails, so I made sure to send him the pic of this colorful gastropod in situ.
The walk back was quite eventful as well. We kept our eyes to the sky for the hope that a little sun may break through, but the thick wall of cloud cover held on with obstinate determination. The yellow flowers of the mesquite-like tepeguaje complimented the low-growing orange of the blossoming lantana, and the discovery of several corona de cristo (gorgeous purple hued members of the passion flower family) by Michael blended together to provide a diverse vibrance to the landscape.
Michael also found a very unusual assassin bug which looked like it could have costarred in the film ‘Hellraiser’ with its orange and black pincushion abdomen.
Best of all (at least in my opinion) was the pair of Trachyderes mandibularis that we found breeding on the trunk of a flowering Baccharis. These large and showy longhorn beetles have been on my lifelist for some time, and spotting them was a definite highlight to the day’s walk.
A big female green lynx spider guarding her newly-hatched brood of spiderlings and a most excellently camouflaged purple crab spider on a blue mist flower provided the finishing touches to a great adventure at the Sal Vieja refuge. As we returned to the vehicle and pointed it in the direction of our next destination, Sal del Rey, the sun peeked out teasingly from the grey mass above us. Stay tuned for Michael’s rendition of our trip to Sal del Rey…