It was a balmy day in Del Rio, a Texas border town about 170 miles west of San Antonio, when a citizen conservationist looking for wildlife stumbled upon a striking rust and orange caterpillar with fleshy horn-like protrusions that are meant to scare predators.

Eventually this larva would become the pipevine swallowtail, an eye-catching butterfly that features black, blue, white and orange hues and feeds on a number of native plants including milkweed.

The glimpse of the caterpillar helped boost the pollinator count in the richly biodiverse region where volunteers and scientists are increasingly trying to gauge whether federal efforts to build migrant barriers could be harming the natural life.

Most worrying to the environmentalists is the planned expansion of a federally-funded wall-in

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