Unidentified flying insects: Mysterious swarms along the Rio Grande bug park visitors

BIG BEND NATIONAL PARK — Just as the park ramps up for a busy spring break season, locals, visitors and park staff are dealing with a group of tourists that have overstayed their welcome — a mysterious species (or several) of small insects along the river corridor. These pests have yet to be formally identified, but have taken a bite out of many folks’ ability to enjoy the grandeur of the Rio Grande canyon country. 

Complaints about these unauthorized campers started popping up on Big Bend social media pages over the winter. Names like gnats, no-see-ums and sand flies have been thrown around but don’t fully explain the phenomenon.

Photos of hikers in head-to-toe bug armor soon followed — nets, buffs, long sleeves and pants tucked into socks. Streetwise Big Bend tourists started showing up to the park dressed for the jungle instead of one of the continent’s most arid destinations.

Back in October, Ten Bits Ranch manager Eden Meadows was on a music float — a leisurely rafting trip down Santa Elena centered around good food and campfire jams — when she and her friends got swarmed during a pit stop at a popular scenic spot.

The altercation left scars that she still bears today. Meadows said that the attack seemed coordinated between a few different species of bugs. “[I was] itching for a week before I realized that creosote salve would stop it,” she said. 

The music float took place at high water — many locals assumed that the bugs had come up with the heavy rains and would subside as everything got drier. Meadows went on another trip a few weeks ago with water low enough that she was able to travel upstream. “They were awful again, but mostly at the entrance to Santa Elena while I was packing up my boat,” she said. 

Around Boquillas Canyon — on the opposite end of Big Bend National Park — a black market has sprung up around the barter and sale of bug nets. Boquillas resident and guide Edgar Ureste was gifted a net by a client and was grateful for the extra layer of protection.

Ureste has lived in Boquillas for most of his life and was taken aback by the aggression of his new neighbors, who arrived toward the end of February. “We’ve never seen anything like it before,” he said. “They get in your eyes, and when you speak they go down your throat.” 

The village of Boquillas depends on tourism — a special port of entry was built in 2013 that allows visitors to cross back and forth on foot, allowing a town four-and-a-half hours from the nearest grocery store to survive. For now, the bugs are mostly a personal nuisance, but Ureste had started hearing stories of visitors packing up and leaving early because of the pests.

Ureste echoed an observation shared by other victims hundreds of miles upriver in Santa Elena Canyon, the Hoodoos and around Presidio-Ojinaga — the swarms didn’t seem deterred by regular preventative measures. “Nothing helps, not even repellent,” he said. “Only the mosquito nets help.”

Joyce Sauer of South Dakota visited the park last month with a friend from Kansas. They did their research ahead of time, and showed up with the necessary protection — which made their stay at the Rio Grande Village campground and hikes along the river comfortable.

Not everyone else they encountered were having as much fun as they were. One fellow hiker jokingly threatened to throw Sauer off a cliff and take her net. They all laughed — but the gag had a glimmer of truth in it. “I could’ve sold at least 30 nets to people who commented on them,” she said. 

Big Bend National Park has yet to put up a non-emergency alert on their official website, but Big Bend Ranch State Park advises “long sleeves and mosquito nets” for visitors within three miles of the Rio Grande. 

River Corridor Superintendent Laura Jennings said that it was too early to make a decision about how the park should respond. “Park staff agree that this is a new phenomenon,” she said. “Without identifying the specific bug species it would be difficult for us to discuss the conditions under which they thrive.” 

Anecdotally speaking, Jennings and her coworkers had noticed that the region’s winter was milder than in past years and did not have significant multi-day freezes. At press time, they had not yet pulled historical data to make a comparison, but they had contacted Texas Parks and Wildlife for more information. 

TPWD invertebrate biologist Ross Winton was on the case — but needed more evidence before he was able to correctly identify the bugs. (Winton advised The Big Bend Sentinel that capturing the insects in a jar and putting them in a fridge or cooler for 15 minutes would slow them down sufficiently for observation.)

For now, Jennings is waiting — and hoping that the annual return of bat species to the park might help cull their numbers. “We are monitoring the situation and looking to see how the species’ life cycles and interactions in the ecosystem play out,” she said. 

Bug nets and other gear can be dropped off for Boquillas residents at the Boquillas International Crossing. Photographs and detailed descriptions of the insects can be sent to Texas Parks and Wildlife staff.