When the Texas Parks and Wildlife Department discovered the pond last September, the shallow waters were thickly carpeted with giant salvinia - a South American invasive plant that conquers ecosystems and devastates freshwater fisheries by blotting out the sun. Open water, fish swimming around and no exotic plants. Giant salvinia can endure up to 48 hours of 3.2-degree weather, outlasting their insect predators, which begin to die in temperatures below 14 degrees, according to a 2015 study by Louisiana State University. The Cow Bayou pond had 80 per kilogram in January, but since all that remains of salvinia in the pond are dead plant leaves, Findeisen and Bowling have nothing to measure. TPWD ensured the weevils would not prey on other plants when they built their Brookeland nursery last year with funds from a $6.6 million Texas Legislature appropriation. Findeisen said Texas residents first shipped the three plants in to decorate their home aquariums, and when they cleaned their aquariums out, they dumped the invaders into backyard streams. Transporting "exotic aquatic plants" is a Class C violation in the Parks and Wildlife Code, subject to a fine up to $500. TPWD has been successful fighting the water hyacinth and alligator weed with pesticides, but the giant salvinia has hairs on its leaves that catch and extend the droplets away from the plant in the shapes of small egg beaters. Enter the weevils, whose success at controlling giant salvinia has spurred TPWD into considering other insects to control other invasive species - such as leafhoppers, which are just as small as weevils, to better control water hyacinth.