Noxious weeds may be one of the biggest problem facing Idaho's landscape. But it's not the only problem. There are other invasive species, that are not weeds, which have the potential to change forever a part of our landscape. The New Zealand mud snail is one such creature.

New Zealand Mud Snail
It’s smaller than a pencil eraser, but don’t let that fool you. This mollusk is causing big headaches for managers of Idaho’s world-famous Silver Creek, in central Idaho.

The problem is that the snail can multiply to such incredible densities that it comes to dominate an ecosystem. In some places in Montana, their numbers have been documented at over 500,000 per square meter, an extremely high density.

The snails feed on the same aquatic plants that support Silver Creek’s abundant insect populations. A dramatic increase in the population of snails could trigger a dramatic decrease in insects. And that could spell trouble for Silver Creek’s famous trout, who rely on insects for food.

There seem to be no practical solutions for killing off the snail, but it is possible to slow its spread.

In 2004 the Nature Conservancy set up a series of wash stations. Anglers are asked to stop and wash their gear after fishing an area known to contain the snails. At Idaho’s most prized fly-fishery, it may be years before the impact of this foreign invasion is fully understood.

Idaho’s 36 Noxious Weeds
Idaho has officially determined that three dozen different weeds are injurious to public health, agriculture, recreation, wildlife, or property. Noxious weeds share some general characteristics: they spread rapidly, reproduce in high numbers, and crowd out native plants. Noxious weeds also tend to be very difficult to control.

In Idaho, noxious weed regulations are covered by Title 22, Chapter 24 of the Idaho Code. Noxious weeds are estimated to have a direct cost to all Idaho lands of $300 million annually. View a complete list of Idaho's noxious weeds.