Snakes: Information for Missouri Homeowners
Robert A. Pierce
Extension Fish and Wildlife Specialist
Department of Fisheries and Wildlife Sciences
Few animals are more disliked or misunderstood than snakes. Irrational fears and feelings that people have about snakes come from misunderstandings and superstitions handed down from one generation to another. Snakes are not mysterious at all, and their colorful, fascinating life histories do not justify the anxiety many people feel about them.
Most of the 50 species and subspecies of snakes found in Missouri are harmless (a subspecies is a geographic race of a species). The five species of poisonous snakes found in the state include the Osage copperhead, western cottonmouth (water moccasin), western pygmy rattlesnake, massasauga rattlesnake and timber rattlesnake. Although you should respect poisonous snakes and approach them with caution, most snakes you may encounter in an urban environment are harmless and beneficial because they eat insects, mice and other rodents.
This publication seeks to dispel misinformation about snakes and to help homeowners control potential snake problems around residences.
Biology and habits
Snakes are reptiles — a group that also includes lizards, alligators and turtles. Reptiles have been around for millions of years.
Snakes are ectotherms, which means they regulate their body temperature by taking heat from their environment or by giving off heat. Because their body temperature is affected by environmental temperatures and varies with surrounding conditions, snakes are inactive during hot seasons (aestivation) and cold seasons (hibernation). Snakes may go for several weeks without eating because of frequent periods of inactivity.
Because snakes are cold-blooded, they must rely on behavior to regulate their body temperature. During the hot part of the day, snakes move to shaded areas. On cool days, they sun themselves on rocks or in warm and open areas. Snakes often seek out paved roads because they are attracted by the heat from the road surface.
Because snakes have a backbone, they are classified in the same group (vertebrates) as fish, mammals, birds and humans. The snake's skeletal system is unique. Snake bones are light and highly movable. The lower jaws and skull are connected by a piece of stretchy material called a ligament. This allows the snake to open its mouth wide and move each jaw independently. Thus, a snake can swallow prey much larger than its head.
Snakes do not have legs, ears or eyelids. Often the sex organs of a snake protrude from the anal plate area, and some might think these are legs.
Snakes use their forked tongues to smell. Their tongue constantly flicks to pick up airborne particles and odors. Once it detects these aromas, the snake inserts its tongue into two holes on the top of its mouth (Jacobson's organ), where its brain interprets the smells. If the snake detects food and is hungry, it will pursue the animal.
Contrary to popular belief, snakes are not slimy. In fact, they feel dry to the touch. The snake's scales and skin help keep it from losing moisture from its body. Snakes shed their skin and eye covering together.
With the warmth of spring, snakes emerge from their winter quarters and search for food and mates. After mating, the male and female snakes separate. Each goes its own way to forage for food until the fall.
Some snakes lay eggs in a damp, protected area where they will hatch in about two months. Other snakes hatch eggs inside the body. Copperheads, rattlesnakes, cottonmouths, garter snakes and water snakes give birth to live young. Once the young have been hatched or born, they are able to take care of themselves. If you find snake eggs around your home or garden, they were laid by a harmless snake.
All snakes are predators, and many are particular about what they eat. Rat snakes eat rats, mice, voles and bird eggs. Water snakes feed primarily on dead, diseased or injured fish. King snakes feed on other snakes, mice, young birds and bird eggs. Some small snakes (the rough green snake) eat insects while others (earth snakes and worm snakes) eat earthworms, slugs and salamanders. Toads are the favorite food of the hognose snake.
When people encounter a snake, they often corner it. Then the snake will hiss loudly, open its mouth in a threatening manner, coil up and strike at the individual or bluff by advancing toward the person. These behaviors are designed to scare off an intruder. They lead, however, to a common misconception that snakes charge or attack people. In most cases, a snake reacts only if it feels threatened. Usually, it crawls away if it can reach cover safely. One exception is the male black racer, which may chase larger animals, including humans, when it is defending its breeding territory.
Snakes like to live in damp, dark, cool places where food is abundant. Likely places to find snakes around homes include
- Firewood stacked directly on the ground,
- Old lumber or junk piles,
- Gardens and flower beds with heavy mulch,
- Untrimmed shrubs and shrubs growing next to a foundation,
- Unmowed and unkept lawns, abandoned lots and fields with tall vegetation,
- Pond and stream banks with abundant debris and trash,
- Cluttered basements and attics with a rodent, bird or bat problem, and
- Feed storage areas in barn haylofts where rodents abound.
Identification of poisonous snakes
All of Missouri's poisonous snakes are members of the pit viper family, and you easily can distinguish them from harmless snakes. Three ways exist to distinguish poisonous snakes in Missouri:
Identifying a poisonous snake by its pupils.
- Pupil shape
Harmless snakes have round pupils (the black part in the center of the eye). Poisonous snakes have egg-shaped or cat-like (elliptical) pupils (Figure 1). In good light, you easily can see the pupil shape from a safe distance because snakes cannot jump, nor can they strike, from more than one-third of their body length.
Poisonous snakes in Missouri also have a conspicuous sensory area or pit (hence the name "pit viper") on each side of the head. The pit looks somewhat like a nostril and helps the snake locate warm-bodied food. It is located about midway between and slightly below the eye and nostril (Figure 1). Harmless snakes do not have pits.
Identifying a poisonous snake by its tail.
- Scale arrangement
The underside scales of a poisonous snake's tail go all the way across in a single row from the anal plate (Figure 2). The tip of the tail may have two scale rows. Nonpoisonous snakes have two rows of scales from the vent to the end of the tail. This characteristic also can be seen on skins that may have been shed.
Other features may help you identify a poisonous snake at a distance
- Head shape
Usually, poisonous snakes have a triangular (wide at the back and attached to a narrow neck) or "spade-shaped" head. Be aware that many other harmless snakes flatten their heads when threatened and may appear poisonous.
- Distinctive sound
Usually, rattlesnakes sound a warning rattle (a buzz or a dry, whirring sound) when approached. However, many nonpoisonous snakes (black racers, corn snakes, rat snakes, milk snakes and pine snakes) and several poisonous snakes (copperhead and cottonmouth) often vibrate their tails when threatened. The sound produced by this vibration often imitates a rattle or hissing sound when the snake is sitting in dry grass or leaves.
You can learn to distinguish poisonous snakes from nonpoisonous species by their color and pattern.
- Color patterns and markings
Snakes with lengthwise-striped markings are nonpoisonous (Figure 3). Most solid-colored snakes also are nonpoisonous, except the adult western cottonmouth, which has dark crossbands that often are indistinct. If a snake is marked in any other way, use other characteristics for identification.
You easily can recognize young cottonmouths and copperheads by their bright yellow or greenish yellow tails.
Snake bites occur despite precautions. Most first-aid texts do not encourage victims of snake bites to kill the snake. The victim may wind up being bitten a second time. Whether the snake is poisonous or harmless can be determined within a few minutes if the victim begins to experience pain and swelling at the bite. Also, all snake bites normally are treated with crotalid antivenom, applicable to all poisonous species in the state, so identifying the snake is not as important as it once may have been.
You should ask your doctor during a regular visit for advice regarding snake bites.
If you are bitten
- Stay calm
- Get medical help quickly
Beneficial aspects of snakes
Before deciding to kill a snake in your yard or garden, consider the many benefits of snakes. Snakes are one of nature's most efficient mouse traps; they kill and eat a variety of rodent pests. Although snakes will not eliminate pests, they do help keep their numbers in check. Some harmless snakes (king snakes, milk snakes and black racers) eat other snakes, including poisonous ones.
Snake venom has been used to develop a variety of human medicines. One type of high-blood-pressure medicine was developed using information based on chemical secrets contained in snake venom. Researchers are conducting studies using snake poisons in developing treatments for blood and heart problems. Snake venom also is being investigated for controlling some types of harmful bacteria.
Snakes in Missouri are protected by state law. The Wildlife Code of Missouri treats snakes, lizards and most turtles as nongame. This means there is no open season on these animals, and it is technically illegal to kill them. Of course, realistic exceptions exist, such as when a poisonous snake comes in close contact with humans, which could result in someone getting bitten. You should get a collecting permit from the Missouri Department of Conservation before attempting to catch and keep a snake.
Controlling snake problems
The most effective and lasting method for discouraging snakes is to modify the environment so they find it unattractive.
Modify the environment by removing the snake's shelter and its food source.
- Lawns and fields kept clean and closely mowed are less attractive to snakes than are areas of tall grass, weeds, brush and junk. Remove other hiding places, such as old boards lying on the ground and piles of rock and trash. Trim shrubs and bushes so limbs are at least 12 inches from the ground.
- Stack fireplace or stove wood away from your home on a rack at least 12 inches off the ground.
- Cleaning around the yard also removes rodent habitat, eliminating a favorite food source for snakes. Also, reduce a snake's food source by placing garbage in sealed trash cans (not bags) away from the house. If you feed pets outside, keep all dog food and cat food cleaned up after each feeding, and store feed in a steel trash can, making it unavailable to rodents.
No fumigants or toxicants are federally registered for snake control. The potential for development of such snake controls is complicated by the diet, body temperature and other biological aspects of snakes.
- Currently, only one chemical for repelling snakes is registered in Missouri. It is available under the brand name Dr. T's Snake Away¨ and contains the active ingredients napthelene and sulfur. However, research has shown that repellents may not be effective under some circumstances.
A snake-proof fence can keep snakes from entering an area, such as the child's play area shown above.
Snakes enter buildings in search of cool, damp, dark areas or places where rodents and insects abound. To prevent these unwanted guests from entering your home, check the foundation for cracks and openings one-fourth inch or larger.
- To seal holes or cracks, use mortar for poured concrete, concrete block or brick foundations. Use one-eighth-inch hardware cloth or sheet metal for wooden buildings. Use caulk to seal cracks and openings around windows, doors, electrical pipes and wiring.
- If you have an open septic tank or sump-pump drain outside, cover the opening with one-fourth-inch hardware cloth. Check it periodically to ensure that the wire does not interfere with drainage.
- If you have young children and live in an area where poisonous snakes are common, you may want to invest in a snake-proof fence (Figure 4). Semipermanent snake-proof fences are expensive to construct, so fencing an entire yard is not practical. However, you can enclose a small area where young children play.
- To construct a semipermanent snake-proof fence, use one-fourth-inch hardware cloth at least 36 inches wide. Bury the lower 4 inches of the fence underground. The fence should slant outward at a 30-degree angle. Place supporting stakes inside the fence (Figure 9 detail). You can make the fence sturdier by attaching wires from the fence to the stakes. If you use a gate, it must fit tightly and should open to the inside because of the outward slope of the fence.
- A more temporary, less expensive design uses a fine-mesh net, buried two inches to three inches in the ground, with metal or wooden support stakes slanted outward at a 30-degree angle for support.
- Keep grass and weeds around the fence mowed close to the ground to prevent snakes from using them to crawl over the fence.
Large glueboard to catch snakes.
Removal from inside buildings
Occasionally, homeowners find a snake inside the home, usually in a basement or crawl space. Snakes are attracted to these areas by the warmth on cold days and the shade on hot days. They may enter through a hole around the foundation or an open or loose door or basement window. If this occurs, you need to get the snakes out, then seal the holes.
You increase your chances of capturing a snake in the house by placing in areas where snakes have been seen some rumpled, damp cloths covered by dry cloths. Snakes are attracted to these areas. You then can remove the whole works, snake and cloths, or capture the snake individually. A good way to remove a snake is to sweep it with a broom into a large bucket.
Another effective way to capture snakes is to use a glueboard. You can buy these in a variety of places, such as agriculture-supply or hardware stores. Most small snakes can be captured using a single glueboard placed against a wall. Keep the board away from pipes or other objects a snake could use for leverage to escape.
A more elaborate arrangement is necessary to capture larger snakes (Figure 5). This type of glue trap can be made at home with purchased glueboards. It is constructed of one-quarter-inch plywood cut into 16-inch by 24-inch sections. Drill a three-quarter-inch hole in one corner to allow removal of the board by using a hook on the end of a long stick. Fasten two to four glueboards (or use bulk glue) along one side of the plywood board. This type of trap, when placed against a wall, is capable of capturing snakes up to 5 feet or 6 feet long.
Use glueboards only indoors or under structures where children, pets or other wildlife cannot reach them. The glue is quite messy and hard to remove. Use common cooking oil or vegetable oil to remove animals from the glue. Be sure to seal any holes or entrances so the snakes do not return. Another option is to use the newly developed snake trap called Snake Guardª. It should be used like a glueboard.
Remember, snakes are an important part of our natural world. The best approach in managing snake problems, where possible, is to leave the animal alone.
Other sources of information
The Missouri Department of Conservation produces publications and videos, a number focusing on snakes:
- One video is entitled A Snake's Tale. You may request a copy from your local MU Extension center, or you can order a copy from the address listed below.
- A brochure on snake identification, entitled Snakes of Missouri (http://mdc.mo.gov/nathis/herpetol/snake/), is available free from the Missouri Department of Conservation.
- The Amphibians and Reptiles of Missouri, by Tom R. Johnson, also is available. This is an excellent reference on Missouri's snakes, turtles, lizards and frogs.
For price and availability of the publications and videos listed above, contact the Missouri Department of Conservation at P.O. Box 180, Jefferson City, Mo. 65102.
Several field guides also are available, including:
- A Field Guide to Reptiles and Amphibians of Eastern and Central North America, by Roger Conant. Peterson's Field Guide series. Houghton Mifflin Co., Boston.
- The Audubon Society Field Guide to North American Amphibians and Reptiles. Alfred A. Knopf, New York.
Outdoor prevention and control tips
- Remove snakes' food and shelter. Keep your lawn closely mowed, and remove debris.
- Control rodents.
- Watch where you put your hands and feet when removing or cleaning debris. If possible, don't put fingers under debris you intend to move.
- Wear snake-proof boots at least 10 inches high or snake leggings if you're in an area where snakes are likely to be found.
- Never step over logs or other obstacles unless you can see the other side.
- If you encounter a snake, step back and allow it to go on its way. Snakes usually don't move fast, and you can retreat from the snake's path.
Indoor prevention and control tips
- Check foundation for holes and cracks, and seal all openings.
- If you find a snake in your home, try to isolate it within a small area.
- You can catch a nonpoisonous snake by pinning it down with a long stick or pole, preferably forked at one end, and then removing it by scooping it up with a flat-blade shovel.
- If you can't remove the snake yourself, find someone who has experience handling snakes to do it for you. A good place to start is your local animal-control shelter or sheriff's office.
- As a last resort, you may need to kill a poisonous snake. Club it with a long stick, rod or other tool such as a garden hoe. Never try to kill a poisonous snake with an instrument that brings you within the snake's striking range (usually less than one-half the total length of the snake).
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