Eastern heath snail (Xerolenta obvia)

Synonyms: Helix obvia, Helicella obvia, Candidula obvia, Xeromphalia obvia

Common Names: Heath snail, heath helicellid, white heath snail

Description:

Eastern heath snail (Xerolenta obvia) is a small, chalky-white land snail from southeastern Europe and Asia Minor that has been introduced to a few sites in North America [1][2]. It was first found in Michigan in 2001 and is also known from southern Ontario and central Montana [1][2]. MISIN tracks it because it feeds on a wide range of plants and crops, gathers in large numbers, and can carry livestock parasites and plant fungal diseases [2][3].

Identification:

The eastern heath snail has a small, low, almost flattened round shell up to about 0.6 inches (16 mm) tall and 0.9 inches (22 mm) across ? roughly the width of a nickel ? with five to six whorls [1][2]. The shell is opaque, chalky white with dark brown to black spiral bands; the outermost band is usually the darkest and the bands fade as they spiral inward [2]. On the underside, the navel (the small central hole, called the umbilicus) is wide open and easy to see, and the oval shell opening is thin and brittle [2]. The body is pale gray [2].

These snails are easiest to spot in the hot, dry part of summer, when they climb up and cluster in large numbers on grass stems, fence posts, signs, and walls to wait out the heat ? often dozens of white shells stacked on a single stalk [2][3]. They come down to feed in rainy, humid weather and shelter under leaf litter over winter, so look for them ? and for chewed plants ? in dry, open, grassy ground [1][3].

At-a-glance cues:

1. Small, low, nearly flat round shell up to about 0.9 inches (22 mm) across, with 5?6 whorls [1][2]
2. Chalky white shell with dark brown-to-black spiral bands, darkest on the outer edge and fading inward [2]
3. Wide-open, obvious navel (umbilicus) on the underside [2]
4. Clusters high on grass stems, posts, and walls during hot, dry summer weather [2][3]

Habitat:

The eastern heath snail favors dry, open, sunny ground. It thrives in heath, dunes and sand hills, open meadows, rocky hillsides, roadsides, and other dry grassy places, and it tolerates heat and drought far better than most land snails [1][2]. During the hottest, driest weeks it climbs up off the ground and seals itself to stems and posts to wait out the heat (a resting state called aestivation), and it shelters under leaf litter through winter [1][2].

The snail is native to southeastern Europe and Asia Minor [2]. In North America it is known from only a few areas so far ? the Detroit area of Michigan (first found in 2001), southern Ontario, and central Montana [1][2]. It is not a picky eater: it feeds on many living and dead plants rather than relying on one host, which lets it survive across gardens, farm fields, and dry natural areas [2][3].

Reproduction:

The eastern heath snail spreads mostly by hitchhiking with people. Because it gathers in large clusters on stems, posts, and equipment, it is easily moved in hay and straw, on vehicles and farm machinery, in gravel and landscaping stone, and in the soil of nursery plants [2][3]. Each snail is a hermaphrodite ? it has both male and female parts ? and it can fertilize itself, so even a single snail moved to a new site can start a population [3].

Snails lay clutches of small white eggs in a shallow hole a couple of centimeters deep in the soil, then close the hole over them [1][3]. Clutch counts range from a few to several dozen eggs, with egg-laying usually peaking in autumn, and adults often die after laying [1][3]. The snails live about two to three years [1]. Because one self-fertilizing snail can found a colony, the best control is to find and remove snails before they lay and to clean incoming hay, gravel, soil, and equipment so new snails are not carried in (see Management) [3].

Impact and Damage:

The eastern heath snail is mostly a plant and farm pest, and it is not poisonous to handle. It feeds on a wide range of plants, including grapes, peas, beans, forage crops, and garden plants, and large numbers can damage crops and contaminate harvested produce [1][2]. There is also a livestock-health concern: the snail can serve as an intermediate host for parasites of sheep and goats, and it can carry plant fungal diseases [1][2][3].

For natural areas, this snail is a worry in dry grasslands and dunes, where it can build to very high numbers, feed on and compete with native vegetation, and crowd native snails [2]. Its habit of massing on fences, buildings, and equipment also makes it a nuisance and helps it spread, and heavy infestations can lead to restrictions on moving hay, produce, and equipment off an infested site [2][3].

Similar species:

A few other small, pale snails of dry, grassy places can be mistaken for the eastern heath snail.

White garden snail (Theba pisana) is another pale, grass-climbing invasive snail, but it is larger and more rounded with a nearly closed navel, unlike the eastern heath snail's flatter shell with a wide-open navel and crisp dark spiral bands.

Carthusian snail (Monacha cartusiana) is a small introduced snail of the same dry, grassy habitats, but its shell is milky white to pale yellow with at most faint stripes, lacking the eastern heath snail's bold dark banding and open navel.

Wrinkled dune snail (Candidula intersecta) is a small pale snail of dunes and dry grass, but its shell is more strongly ribbed and usually lacks the eastern heath snail's sharp dark spiral bands.

Monitoring and rapid response:

Signs to watch for:

1. Chalky-white, dark-banded snails clustered high on grass stems, fence posts, signs, and walls during hot, dry summer weather ? often many on one stalk [2][3]
2. Chewed leaves on garden plants, vegetables, grapes, and forage in dry, open, grassy areas [1][2]
3. Lots of small white snails turning up after hay, gravel, landscaping stone, or equipment is brought onto the property [3]

What you can do:

1. Hand-pick snails ? easiest when they cluster on stems and posts in summer ? and drop them in soapy water or seal them in a bag for the trash [2][3].
2. Remove leaf litter, debris, and dense grassy cover near gardens and buildings to take away shelter [1][2].
3. Inspect and clean incoming hay, straw, gravel, soil, nursery plants, and equipment for snails and eggs before bringing them onto your property, and don't move infested material [3].
4. Natural area crews can survey dry grasslands, dunes, and roadsides, focus first on small outlying populations to stop spread, and clean snails off boots, vehicles, and machinery between sites [3].
5. Report sightings (below) ? this snail is known from only a few North American sites, so early reports are valuable [1][2].

When to call a professional:

1. Established or spreading populations, or damage to a crop, vineyard, or forage field ? contact your local cooperative extension office or state agriculture program for current guidance [2][3].
2. For chemical control options, contact a licensed applicator or your local cooperative extension office.

Report sightings to MISIN. Help track this species' spread by submitting observations through the MISIN web site or the MISIN mobile app (Android, iOS, Windows, and macOS). Photos at multiple angles paired with a precise GPS location are the most valuable data for confirming new occurrences and triggering rapid-response review.

Credits:

1. Michigan Department of Natural Resources, Invasive Species Program. Heath Snail (Xerolenta obvia). michigan.gov/invasives
2. Montana State University Extension. Eastern Heath Snail (Xerolenta obvia). montana.edu/extension
3. Oregon Department of Agriculture, Insect Pest Prevention & Management. Pest Alert: Eastern Heath Snail (Xerolenta obvia). oregon.gov/oda

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