Indian River County Extension Service

Picture this - it’s late summer and you are walking through your Florida Yard after a heavy rain. You notice a small rock roll slowly across your path, and you stop to observe it more closely: A trail of slime follows it, and you realize it’s not a rock after all - it is one of the snails that can be found in our local Florida Yards.

NATIVE TREE SNAILS

All native Florida tree snails live their entire lives hanging onto tree branches. There are other introduced snails that may also share trees as their home, but they also live in leaf-mold, under or near rocks, or on rock faces. Because they need high humidity and warm temperatures, they are restricted to tropical and semi-tropical regions. Many are quite colorful, and as a result, some have become endangered because of over-collection. More significant threats to the tree snails are habitat destruction and the over-application of pesticides and fertilizers. Tree snails should not be collected as they are not pests and may actually be beneficial, as they feed on epiphytic growths such as algae, fungi, and lichens on trees.

Native tree snails are generally cone shaped and may reach ½ to 2 ½ inches in length. Their shells vary in color from ivory to tan, often brilliantly colored with yellow, green, pink, and brown markings. Shell surfaces are smooth and sometimes glossy. These animals are most often found in native hammock trees and shrubs, but frequently live in citrus groves and backyards.

Eight distinct native tree snail species are found in Florida, with some species having hundreds of different color forms. Of these species, three may be encountered in our area. The most likely native tree snail to be found in the Indian River area is the Manatee Tree Snail (Drymaeus dormani). Its shell measures about an inch in length, and has 3-4 wide spiral rows of chestnut-brown squares on the shell. The markings can be faint to lacking in some specimens. This species is found north of Lake Okeechobee, and has been reported on palmetto, orange and grapefruit trees, which is why it is sometimes called the Citrus Tree Snail.. I found an old advertisement in our files from a grower in Leesburg who was selling these snails as a means to reduce mites and scale insects in citrus groves; the theory was that their slimy trail would provide a physical barrier to these sucking insects.

Two other Florida native tree snails may occasionally be spotted wandering on our local trees. The reported natural range of these snails is further south of our area, but with the absence of freezing temperatures since 1989 and the use of more native plants that have come from nurseries south of here, there have been reports of the next two tree snails on our region.

The shell of the Many-lined Forest snail (Drymaeus multilineatus) (right) has vertical chestnut brown stripes with a blue to black apex, and sometimes has 1/16 inch wide bands that surround the shell. This species is found on the ends of trees and shrubs twigs in the southern Florida, and is equally at home on either native or exotic plants.

The Dominican forest snail (Drymaeus dominicus) (left) has a shell slightly less than an inch, with 3-5 irregular narrow brown bands, which can be unevenly broken or even lacking. This species differs from the Manatee snail by a more rounded shell shape, smaller size, and it lacks a flared edge. It’s range is generally south of Lake Okeechobee, and has similar host plants - citrus and native trees.

Not all of the snails found in our Florida Yards are desirable. One that can cause considerable destruction to our ornamental plants is the imported Cuban brown snail (Zachrysia provisoria) (above), which was purposefully released in Miami during the early 20th Century. It measures 1 to 1 ¼ inches in size, and is rounded in shape, with four to five rapidly expanding whorls. This is a dirty brown color and sometimes has light brown streaks. It cannot be confused with any other species in south Florida due to its large size and strongly ribbed shell sculpture. The Cuban brown snail lives among leaf litter and often finds its way into ornamental plantings. It is a voracious plant eater, and causes significant damage to ornamental plants in south Florida. A few years ago I visited a commercial landscape in Vero Beach, and was crunching snails with each step I took. Their rasping mouthparts were strong enough to strip the bark and cambium layer off of pittosporum and oleander stems.

If you have an outbreak of pest snails or slugs (mollusks without shells), there are plenty of folklore suggestions available to deal with them, much of which can not reliably manage runaway snail populations. University of Florida research indicates that effective methods of dealing with them include the following steps:

Remove excessive organic material under plants. Organic materials provide moist hiding places for eggs and smaller snails, and sometimes can be consumed as food sources. While the use of mulch in Florida Yards is generally encouraged, if an out- break of snails is plaguing you landscape, consider pulling it back and stockpiling it for a period of time to discourage damaging snail populations.

Check your moisture situation. You can’t do anything about the amount of rainfall we receive, but, there may be some steps that can be taken to encourage more rapid drainage of water from snail infested areas. And turn off the sprinkler - much of the time, summer rains will supply more than enough water for established landscape plants.

If the infestation is not too large, hand-picking is one of the best control methods. It takes persistence and labor, but is reasonably effective, non-toxic, and environmentally acceptable. If you can’t bring yourself to crush them, freeze them for a few days, then trash them.

Use of pesticide baits. Look on the labels for molluscicides containing the active ingredient metaldehyde, a poison that is made into pellets and spread under effected plants late in the day when rain is not expected. Be careful when using this product around curious children or foraging pests or wildlife.

Edible Snails

One suggestion sometimes made for management is to collect these snails and use them for a favorite French delicacy - escargot. The problem with using locally collected snails in this way is that they may have fed on poisonous plant such as oleander, and may lack the level of sanitation necessary for proper human consumption.

Commercial heliciculture (the growing of snails) uses the Petit-Gris or the Gros-Gris (Helix aspersa) (see left photo) for escargot production.  These snails are raised in sanitary snail farms and are fed special snail feed. These species are now a common pest in California and could also be a problem here in Florida; this is why several states prohibit the raising of snails.

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For information about the Giant Africa Land Snail, go to the UF/IFAS Okeechobee news article, May 19, 2004

For more information about Florida Tree Snails, go to the UF/IFAS Featured Creatures Article

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The Florida Cooperative Extension Service - Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information, and other services to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin. Florida Cooperative Extension Service / IFAS /University of Florida. Larry A. Arrington, Acting Dean.

Last update: 05/19/2004 .  This page is maintained by Dan Culbert