State officials could start efforts to control an invasive snail near Belt, in May.

The Montana Department of Agriculture became aware of a population of eastern heath snails in parts of Cascade and Choteau Counties in 2012. The department has since drafted an environmental assessment, now in the public comment phase, with proposals to cull the snails.

The agency does not know how the snails got to Montana, but residents have reported seeing the snails for at least 25 years, said Ian Foley, pest management program manager for the Department of Agriculture.

“It’s fairly different and odd for Montana to have an invasive dry land snail,” he said.

Because the snail lives on dry land it falls under the jurisdiction of the Montana Department of Agriculture. If it was an aquatic invasive species, such as the better known zebra mussel, jurisdiction goes to the Department of Fish, Wildlife and Parks, he said.

The snails become pests in grains and other commodities causing quarantines, Foley said.

The only other populations in North America are in Detroit and Ontario at shipping yards. The invasion is rare enough in Montana that the USDA’s malacologist, or specialist in snails and slugs, came to advise the state department, Foley said.

The infested area encompasses nearly 100,000 acres, but snails are concentrated along highways, the town of Belt, Armington Junction and Sluice Boxes State Park. Given the widespread range of the snail, total eradication would be unlikely, the environmental assessment said.

The preferred alternative under the environmental assessment calls for continued monitoring of snails as well as education and outreach to impacted landowners. The agency would then conduct voluntary suppression efforts using pesticides called molluscicides.

The two molluscicides identified in the assessment are iron phosphate, which is non-toxic and common in law fertilizers and metaldehyde, a slightly to moderately toxic substance that quickly dissolves when wet.

Although the snails are fairly concentrated in the Belt area, officials worry that they could make it to the Missouri River. At that point, they could easily catch a ride downstream to other parts of Montana and even other states.

After public comment, the department will make a decision on their choice of action. If they decide to proceed with using molluscicides, application could begin in the first couple weeks of May, Foley said.

The public has until April 15 to comment on the environmental assessment. Written data, views, or arguments may be submitted to: Cort Jensen, Department of Agriculture, P.O. Box 2000201, Helena, Montana, 59620; telephone (406) 444-3144; fax (406) 444-5409; or email, and must be received no later than 5 p.m.

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