Farmers are being asked to watch for a species of dryland snail showing up in north-central Montana hayfields, pastures, highway right of ways and ditch areas. State ag pest management officials are concerned the Eastern heath snail will become invasive.

Right now, the pest is more of a contaminant that can affect hay quality. “They’re not like alfalfa weevils or grasshoppers where their presence is going to affect yields,” says Gary Adams, state plant health director for USDA’s Animal and Plant Health Inspection Service (APHIS).

Concentrations of 70-100 snails/sq ft have been reported. “It’s an amazing biomass of snails,” says Ian Foley, pest management program manager for the Montana Department of Agriculture (MDA). “In some areas of the Belt Creek Drainage Area (where the species was first discovered), when you look at the ground, you’re likely to see more snails than anything else.“


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Smaller than a dime, the mollusk has a white, circular shell with cream or brown banding. In Australia, high populations of similar species of snails can clog farm machinery; the slime they produce can make hay so distasteful that livestock won’t eat it.

No one is sure how the snail, native to southeastern Europe, got to Montana. Anecdotal information suggests the species may have been in the state for 30 years before it was first confirmed in 2012, APHIS’ Adams says.

“You’ll see the same kind of thing with some invasive weed species,” he adds. “They’ll stay at very low populations and may not be noticed for 50, 75 or even 100 years. Then, when the conditions are right, the populations will explode. We don’t know what this snail is going to do, but it could react similarly. At this point, we’re still learning.”

Record rainfall in 2011 may have played a role in the current snail outbreak; the pest tends to multiply after wet weather.

MDA has federal Farm Bill funding to work with chemical companies on suppressing and containing snails. A major goal, says Foley, is to keep them out of the main stem of the Missouri River. “If they get in there, they could float to all of the downstream states,” he says. Another goal is to hold snail populations in check to avoid a quarantine on the movement of hay and other crops out of the area.

For now, MDA and APHIS are focusing on raising public awareness of the snails’ presence. “We’re trying to get better idea of where the snails are and where they are not,” says Foley. “We’re asking farmers, ranchers and other landowners to report any suspect invasive snails to our office so we can check it out.”

Reach Foley at 406-444-9454; Adams at 406-449-5210.

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