Hard-to-kill snails infest Santa Monica Mountain watersheds - latimes.com

Hard-to-kill snails infest Santa Monica Mountain watersheds

Even Formula 409 has proven ineffective at destroying the New Zealand mudsnail, an asexually reproducing invasive species that poses a threat to steelhead restoration efforts and native creatures.

Researcher Jack Topel looks for New Zealand mudsnails in Medea Creek. (Brian Vander Brug / Los Angeles Times)

They're nearly always pregnant, like the mythical tribbles of "Star Trek" fame. They pass through gullets of fish unfazed. And they could bring disaster to native bugs, frogs and steelhead restoration efforts in the Santa Monica Mountains.

New Zealand mudsnails have taken over four watersheds in the Santa Monica Mountains and are spreading fast, expanding from the first confirmed sample in Medea Creek in Agoura Hills to nearly 30 other stream sites in four years.