On a warm, sunny day, anyone who visits a fresh body of water can find dragonflies darting about as they feast on insects. What is less obvious is that dragonflies successfully capture their prey 95% of the time.
This research, published in the Proceedings of the National Academy of Sciences in 2012, revealed dragonflies are among the most efficient and lethal predators on Earth.
Dragonflies and damselflies belong to the scientific order Odonata, or “toothed one” as it’s translated in Greek, which refers to their serrated teeth.
These aquatic invertebrates are fascinating for many reasons, but the most important is their unspoken agreement with people to hunt pest mosquitoes.
“The enemy of my enemy is my friend” is an ancient proverb that holds true to the relationship we have with dragonflies.
A single dragonfly can consume hundreds of mosquitoes per day. An ally like that is worth keeping around, which is exactly what Harris County Precinct 4 Commissioner R. Jack Cagle had in mind when he suggested turning a run-of-the-mill detention basin into a dragonfly habitat.
“We transformed an ugly stormwater drainage hole in the ground into a place where our beautiful but voracious winged friends can thrive and entertain us,” Cagle said.
Detention basin transformed
When planning started for the expansion of Telge Road at Spring Cypress in northwest Harris County, an agreement was forged so the Harris County Engineering Department could construct the detention basin on land owned by the Harris County Flood Control District (HCFCD).
After completing the first phase of the road project in early 2019, including updates to the bridge across Little Cypress Creek, the detention basin and land were transferred back to HCFCD for maintenance.
“Our department helped design the basin to create a wetland habitat,” said Stephen Benigno, the district’s environmental quality section leader. “Basically, when the water enters in, it leaves cleaner. We do this in all of our detention basins.”
The state of Texas requires that a stormwater quality enhancement feature is included in every HCFCD project.
One of the most cost-effective and easiest ways to accomplish that is by creating wetland habitats. Wetland ecosystems can improve stormwater quality because the ponds allow pollutants and sediment to settle out in the water, and the vegetation traps and filters contaminants.
The basin is a wet-bottom detention, featuring emergent plants like cat tails, bull rush and lily pads that are immersed in water. These plants are harvested from the HCFCD self-sustaining nursery, where staff members propagate wetland species to reduce project costs.
“We also knew that Commissioner Cagle had requested it to be a dragonfly basin, so we tweaked the design to create a little extra wetland area,” said Benigno.
Anita Schiller, director of Precinct 4’s Biological Control Initiative, was asked to consult on the basin design to ensure beneficial wildlife, such as dragonflies and damselflies, would be incorporated. Additionally, Schiller was tasked with introducing native, non-game fish species and native, aquatic carnivorous plants to keep the basin from becoming a mosquito breeding ground.
“This particular project is exciting because it is a showcase for best practices when different departments with different objectives come together,” Schiller said.
Schiller and her team released native dragonfly and damselfly nymphs at the basin since they not only feed on mosquitoes in the adult stage of life, but they are also relentless mosquito predators in the larval stage.
Additionally, Schiller introduced carnivorous bladderwort plants to serve as natural barriers to discourage mosquito breeding in the basin.
“We’re speeding up establishment of mosquito predators since this basin is newly constructed and the ecosystem is unbalanced,” explained Schiller.
Another motivation to create a dragonfly habitat at the Telge Road Detention Basin was preservation of these beneficial allies. There are 90 distinct species of Odonata in Harris County and more than 5,000 worldwide, but one in six species in North America is at risk of extinction, including some along the Gulf Coast.
Restoration and conservation combine
“If you look at a map of Houston, the old historic aerials, Houston was built on prairies,” said Benigno. “There are maybe some patches here and there now, but it’s great to do what you can to restore it.”
Benigno wanted to create a prairie at the site to help attract native insects, which would in turn contribute to the dragonfly habitat. But the goal transformed when Houston Wilderness, a nonprofit dedicated to protecting, preserving and promoting the eco-regions in the Greater-Houston area, approached Benigno in the spring of 2019.
“We were able to partner with Houston Wilderness through their Monarch Flyway Strategy Grant to get 500 prairie plants and 30 pounds of native seed. It’s not something we typically do on basins, but in this instance, we were able to make it work,” said Benigno.
The Texas Monarch Flyway Strategy is a statewide effort to restore, increase and enhance monarch habitats across four major regions that serve as critical links in the migratory journey of monarch butterflies.
At just 7 acres, the footprint of the Telge Road Detention Basin is smaller than many HCFCD properties. With the mission to transform the basin into a dragonfly habitat and the unique arrangement of the land next to the basin, HCFCD jumped at the chance to restore the adjacent prairieland.
According to Benigno, the prairie ecosystem is almost endangered due to urban sprawl and rural and agricultural development.
“A prairie doesn’t have that grand visual aspect of a mountain or even a forest. It’s just a bunch grass and wildflowers,” Benigno said. “But if you really get down in it, you start to appreciate it more. It has an incredible amount of native diversity. It’s Houston’s natural heritage, it’s what we were built on and, in many cases, it’s overlooked.”
The wetland and dragonfly portions of the basin plan had been in the works since the beginning, but the prairie addition to benefit pollinators was implemented toward the end of the project.
Another distinctive feature of the property is its proximity to Precinct 4’s Little Cypress Creek Preserve and connectivity to its trail system through a pedestrian passageway that goes underneath Telge Road.
Unique opportunity forges unique partnerships
“We purchased the prairie plants from Houston Audubon with funding from Houston Wilderness, we got the equipment from Trees for Houston, and then NRG coming in with their volunteers – it really was a very collaborative process between everyone,” said Benigno.
Volunteers with NRG Energy joined HCFCD to plant more than 20 native coastal prairie species, including milkweed, swamp sunflower, big bluestem and gamagrass, in a 1-acre section of the Telge Road Detention Basin.
NRG Vice President of Operations Bill Evans said the volunteers were excited to help with the project, especially after learning about the various partners involved and the unique goals of the site.
“Our volunteer team wanted to pick up some shovels, get our hands dirty, and take an active role in transforming the site and restoring this habitat,” said Evans.
“The detention basin itself is there for flood reduction,” Benigno said. “And then installation of the wetland plants is for our stormwater quality permit and to help stabilize the soil. Then the prairie plants are there for all the additional benefits: the dragonflies, the monarch butterfly strategy, and prairie restoration. Plus, the basin being part of the Little Cypress Creek Preserve system makes this a multi-use facility.”
It may be a long time before the stars align again with a site featuring ideal circumstances that achieve so many varying goals at one time. Until then, this project is an example of the success that comes from unique partnerships.
To learn more about the Harris County Flood Control District’s Stormwater Quality Program, visit hcfcd.org. For more information about Precinct 4’s Biological Control Initiative, check out hcp4.net/bci.