MISSION, Texas (Border Report) — The U.S. Fish and Wildlife Service wants to put on the endangered species list rare milkweed that is found in two South Texas counties, but Texas officials are balking because it could interfere with state border security plans.

Texas Attorney General Ken Paxton this week sent a letter to the federal agencies saying that listing prostrate milkweed as an endangered and critical habitat would risk security on the Texas-Mexico border.

A species of milkweed is seen April 21, 2022, at the National Butterfly Center in Mission, Texas. (Sandra Sanchez/Border Report)

If the prostrate milkweed were to make the list, then the area where it grows — in Starr and Zapata counties — would be exempt from border barrier construction. And that could halt the construction of a border wall that the state of Texas currently is building outside of the town of La Grulla.

The state is funding millions of dollars to build its own wall, which is nearly 2 miles long and the first phase nearly complete.

Texas Gov. Greg Abbott has said the state plans to build more sections of wall throughout Starr County.

But the finicky and hard-to-grow prostrate milkweed species could stop border wall plans.

In his Monday letter, Paxton wrote that “the decision to designate critical habitat requires more than merely determining that the prostrate milkweed species is at risk. The designation determination must also account for the potential implications to border security, which implicates national security, Texas’s security and economy, and other public policy priorities, such as combatting human and drug trafficking, which are rampant in areas near the border.”

Teas Gov. Greg Abbott watches Dec. 18, 2021, as a panel of state-funded border wall is built in rural Starr County outside La Grulla, Texas. (Sandra Sanchez/Border Report File Photo)

U.S. Fish and Wildlife officials feel otherwise.

The agency in February announced their proposal to put 691 acres of critical habitat under protection to safeguard the prostrate milkweed, one of several milkweed species that the beloved monarch butterflies need in order to survive.

“This listing and critical habitat proposal is based on the best available science,” the agency said. This “will help raise awareness about the threats to this plant and inspire diverse partnerships on its behalf.”

“Prostrate milkweed’s flowers attract and support native pollinators, especially large bees and wasps, and it is a host plant for monarch butterflies,” said Chris Best, state botanist for the Fish and Wildlife Service in Texas. “Unfortunately, this species is negatively impacted by competition from introduced buffelgrass and increased development in its native Tamaulipan shrubland habitat.”

Prized monarch butterflies can only lay their eggs on milkweed species and the prostrate milkweed makes up a significant habitat for the development of their larvae, National Butterfly Center Executive Director Marianna Treviño-Wright told Border Report.

“All milkweed species are important to monarchs and their ability to reproduce, especially as they’re headed back through Texas after over-wintering in Mexico because they’re looking for milkweed to lay their eggs on,” Treviño-Wright said as she perused the center’s vast borderland grounds on Thursday looking for various milkweed species.

National Butterfly Center Executive Director Marianna Treviño-Wright stands in front of a patch of milkweed on April 21, 2022, at the nonprofit located on the border in Mission, Texas. Monarch, as well as queen and soldier butterflies must lay their eggs on milkweed in order to survive. (Sandra Sanchez/Border Report)

Her nonprofit is located in Hidalgo County, just east of Starr County, where the soil has too much clay for prostrate milkweed to grow. But there are several other species of milkweed on the premises that attract butterflies, such as tropical milkweed and zizotes milkweed, all of which attract monarchs and their cousins, the queen and soldier butterflies, she said.

Millions of butterflies migrate north and south through this eco-corridor of the Rio Grande Valley leading to Mexico every year.

The colorful tropical milkweed species is seen at the National Butterfly Center in Mission, Texas. (Sandra Sanchez/Border Report)

Fish and Wildlife Service held a public commenting period that ended on Monday, the same day that Paxton sent his letter.

Treviño-Wright said she hopes the federal agency will decide to list the prostrate milkweed on the endangered species list to help butterflies, and to prevent future border wall construction, which she says is not necessary and militarizes the border region.

“The federal government has the ability to waive every law including the endangered species act covering plants and animals for border wall construction. The state doesn’t have that authority so if the state wants to continue building they risk running amok, running afoul of the endangered species act for their plans if the prostrate milkweed is listed,” she said.

The National Butterfly Center will open to the public on Saturday after being closed since late January due to a security threat by far-right organizations, Treviño-Wright told Border Report.