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Dealing with Snakes Around Homes

"Arrgh! There's a snake in the yard!" This is often the reaction of people who come into contact with these common Midwestern wildlife. Unfortunately, in our hysteria, we often strike out at these creatures--with shovels, hoes, even lawnmowers--with lethal results. Our fears are often the result of a combination of childhood experiences and a great deal of misinformation. Educators find, however, that if we can replace the myths about these animals with facts, the fear is very often replaced with interest. Indeed, truth often is stranger than fiction!.

Garter snake, a common, harmless Iowa snake.Snakes are reptiles. As such, they have a backbone, often with over 300 vertebrae. They are "cold-blooded", taking their body temperature from their surroundings and therefore, seeking winter places that remain above freezing. They lay eggs and do not care for their young after birth. Two Midwestern types, garter snakes and rattlesnakes, retain their eggs inside their bodies until they hatch, imitating a type of "live" birth typical of mammals.

The skins of snakes are smooth and dry, feeling much like the leather on your shoes. Most Midwestern snakes see poorly and cannot wink at you: they have no eyelids! Instead their eyes are covered by a clear single scale that is shed and replaced each time they shed their skin. While lizards have external ear openings, snakes have none. Their main sense organ, then, is their tongue. It is constantly flicking out, "tasting" molecules from the air to detect what is around them. Unlike humans, a snake's tongue is not used for swallowing. Rather, snakes have rows of tiny curved teeth and separated jaws to "walk" their prey down their throat.

They move by means of the rhythmic movement, called "peristalsis", of muscles on their bottom side. This movement allows the broad, strong scales on their belly ("scutes") to push against rough surfaces and move forward. Having no legs or feet, they cannot dig holes but can occupy dens made by small mammals like ground squirrels and chipmunks. They are extremely important predators, eating a variety of insects, grubs, worms, amphibians, and especially rodents.

The 28 species of Iowa snakes range from the tiny and uncommon 7-inch western worm snake to the common bullsnake which can be over 5 feet long. Most common are several species of garter snakes, the fox snake and the bullsnake, all of which are harmless. Timber rattlesnakes are venomous and can be common in some very localized forested areas of the state. All other venomous snakes are either exceedingly rare or absent in most of the state.

Follow these tips for keeping your house unattractive for snakes: 

  • Do not feed birds from April to October. Birds do not need supplemental food during the growing season and feeders draw in rodents and other small critters, which can draw in snakes. Snakes will hibernate from November until March, meaning homeowners don’t have to worry about encountering any in the yard.
  • Keep the lawn mown short. By keeping the lawn very short, snakes are at an increased risk of being eaten by a hawk. Snakes do not like to put themselves in such situations and will generally avoid such areas, thus keeping them away from the house.
  • Keep landscaping near the house simple. Avoid rock walls and similar features that draw small animals that snakes like to eat into the area. Also avoid “ponds” and similar features that attract frogs, or that hold small fish that garter snakes like to eat. Keep plantings to a minimum, particularly around buildings, as these provide shelter for both snakes and the prey items they eat.
  • Keep areas around the house free of wood piles, debris, etc. Snakes can use these to avoid hawks and other predators and to control their body temperature.
  • Install rubber seals on the bottom of any garage or shed doors. This will help keep snakes out of those buildings.
  • Check the foundations of buildings and structures. Snakes will often use people’s basements or old cisterns as places to hibernate, and snakes have a tendency to be faithful to those sites. Make repairs between May 1 and October 1 so snakes are out and active and not trapped underneath.

The best recourse when you find a snake in a dwelling is to direct it into a container with a broom and then release it on another area on your property away from your house. Then consider the recommendations above to reduce the attractiveness or accessibility of your home to snakes and other unwelcome critters.

Snakes don't do any direct damage to buildings because they don't dig their own holes, instead using holes other animals have made. Although snakes elicit strong negative reactions among many, Iowa’s native snakes play important roles in the state’s ecosystem, often doing more good than harm for a homeowner through their appetite for more problematic rodents and insects. Managing property to reduce potential attractiveness for snakes is the best way to ensure they play this important role where they belong - outside the home.

For more information about snakes check out our Iowa Reptiles and Amphibians publication or the Iowa Herpetology website

Photo credit: Garter snake, Mark Wilson,


There’s a mouse in my house!

The coming of every fall often also brings with it something else: mice! Two species of mice native to Iowa are seasonal visitors to homes in which they can gain access. The deer mouse and wWhite-footed mousehite-footed mouse make their way into homes in search of winter shelter after having spent the spring and summer outdoors raising young and foraging. The aptly named house mouse on the other hand, will live year-round in your home without the seasonal migration. Requiring enough space to fit their head through, about ¼ inch or larger, both outdoor species will bring in nesting material or create their own inside, chewing apart paper, insulation, foam and any other material deemed suitable for a cozy nest. These mice also begin stashing food, such as corn kernels and bird seed, which they survive on for portions of the winter.

Exclusion is the preferred method of avoiding the seasonal visits of deer mice and white-footed mice. Look for gaps in siding where the siding meets the foundation or where pipes and other utilities enter. Cracks in foundations and loose-fitting doors without proper weather stripping are other obvious places where mice can get in. And, because mice are good climbers, don’t forget to check for poorly-fitted windows and disrepair around the roof, including attic vents. Mice can easily travel within walls, and without a way into the living quarters, you may never notice them. Repairs to exterior openings are necessary to avoid costly damage to wiring and other fixtures of your house. Rodent-proofing can be as simple as adding or replacing weather stripping on doors and windows, which will reduce your heating costs, to filling cracks and holes with an expanding foam sealant. Because mice are chewers, it is recommended to tightly pack steel wool into the gaps first, and then apply the foam. Metal flashing will also create a chew-resistant barrier over openings. Other kinds of repairs may be necessary, depending on the location.

A pen illustrates a small hole where a natural gas pipe comes into a house, leaving enough space for a mouse to get in.Trapping is necessary to remove mice already inside. Several varieties of traps are available, including the snap trap and the box trap. The snap trap, such as the Victor® EasySet, is a kill trap and can be baited with peanut butter or moistened rolled oats. Mice travel along the edges of and behind objects, taking advantage of the protection and cover this provides. Set traps against walls, along likely travel routes, and behind objects where you have seen or suspect mice. Their droppings provide a clue to where they have been. You can improve your chances of catching mice by setting multiple traps in different locations. Consider setting two together with the bait sides opposite each other. The box trap is a live trap, which includes the Victor® Live Catch and the Victor® Tin Cat Repeating Mouse Trap. The latter is ideal if you have more than one mouse in the house. This trap has two chambers, one where the mouse enters and one where the mouse goes when it is caught. The trap is designed to automatically reset itself so that multiple mice can be caught at once. The trap works without bait and relies on the natural curiosity of mice. Again, these traps should also be set against walls and along likely travel routes. Mice can be released outside, but complete repairs so these same mice do not return.

Keep in mind this additional information. First, properly store grains and other seeds in rodent-proof metal containers and avoid leaving food out overnight. We do not recommend poisons as an initial solution unless all other methods have been unsuccessful. Use of poisons can be a risk to pets and children and often means mice die in inaccessible places, which can cause order problems. Also, glue traps, while effective at catching mice, are also not recommended, as this is generally messier and subjects the mice to a slow death due to starvation and injury. Finally, ultrasonic devises labeled as rodent repellants do not live up to company claims and independent research has not shown they are effective at rodent control.

Photo Credit: White-footed mouse, D. Gordon Robertson,; Mouse entry hole,

Reference to brand names should not be taken as an endorsement but rather is used to illustrate available methods.


Vertebrates in the Vegetables!

Perhaps nothing is as frustrating to a gardener as losing their hard work and crop to unwelcome wildlife. After working hard all spring to get plants and seeds into the ground, fighting the weather, and conquering the weeds, just when the harvest is to begin some other vertebrate critters begin to harvest the plants. Rabbits, ground squirrels, tree squirrels, pocket gophers, or deer arrive to take advantage of the plantings you have provided--assuming you provided food just for them!

The two major defenses gardeners have against such competition are: repellents and exclusion. Repellents are either area repellents or taste repellents. Area repellents repel the animal by smell. As the name implies, the chemical is aromatic and fills the air in the general area of the planting. The smell is offensive to the animal and it avoids the area. Examples of such repellents include hanging bags of human hair or bars of soap or commercial products like moth balls (naphthalene).

Taste repellents are more effective in that they are applied directly to the plant and repel the animal by having a bad taste. The idea is that the animal may sample the plant once, but the bad taste keeps it from trying it again. Examples include such "home remedies" as cayenne pepper and commercial products containing such chemicals as thiram, putrescent egg solids, or other foul-tasting products.

Repellents are not, however, a cure-all. Area repellents are limited in effectiveness, but may be useful if placed around the perimeter of the garden area. Taste repellents cannot be applied to plants you intend to eat since you would also find the taste offensive, and thus are mostly useful in landscaping. Most repellents must be reapplied regularly, especially after rain or periods of extreme heat. Not all products are registered for or effective against all species. And, if an animal is hungry enough, they will often ignore the bad smell or taste. Despite these limitations, many gardeners may find repellents to be the best alternative in their particular circumstance.

Another more permanent protection against unwanted sampling of your garden is exclusion. You may exclude in several ways, depending upon the area you are in and the situation. Individual plants may be surrounded by plastic tubes, chicken wire, or hardware cloth fences. You may also fence off your whole garden area to exclude the worst offenders – rabbits and deer.

The size and mesh of the fence depend upon what you are trying to exclude. For rabbits, 1-inch mesh "chicken-wire" fence at least 2 feet high will successfully exclude them, especially if the bottom 2-3 inches are buried below ground level. For deer, you may use a variety of fences including electrical tape or strong large mesh of any kind. Old "hog wire" fencing filling many farm gullies will suffice, especially if several sections are erected, reaching a height of 8 feet. In small garden plots, you may be successful with fences somewhat shorter than that, but no lower than 5-6 feet.

Gardeners may find also that general clean-up of garden areas to eliminate the brush, log, or junk piles that provide protective cover for many of the offending critters will help. Also, the presence of pet dogs will often serve as an aversion to these wildlife.

Above all, keep in mind that a reality of gardening is dealing with pests and factors out of your control like weather. Gardens inevitably attract both those critters you want and those you don't. Some damage should be expected. When your tolerance level for such damage cannot be raised any higher try some of these repellent or exclusion methods.




Pee-Yew! It's fall and you've caught a whiff of that unmistakable pungent smell drifting on the night air that could only belong to the skunk. Skunks, now classified in the family Mephitidae, like members of its former family Mustelidae, the weasels (mink, weasel, badger, otter, etc.), emit an oily musk from their anal glands. Members of these families use musk to mark territories and den sites, and attract a mate. But, in the case of skunks, they can release a potent mist or stream, at close range and up to 20 feet, to defend themselves against predators!

An example of rolled sod by foraging skunksIowa has two species of skunks: the striped skunk and the spotted skunk. The latter, also known as a "civet cat", is smaller than the striped skunk, has white spots and shorter, broken white stripes against black fur, and is listed on Iowa’s endangered species list. Little is known about where they may still be found in Iowa. With the loss of small farms, diversified agriculture, and the lack of rodent prey attracted to readily available grain, once stored in open cribs, the “civet cat” has all but disappeared from Iowa’s farms and countryside. Meanwhile, the striped skunk has remained ubiquitous, occasionally to the chagrin of a dog or homeowner.

Striped skunks are typically nocturnal, but during times of increased feeding, such as spring when the female is pregnant and fall, when fattening up, they can be seen earlier in the day or evening. Seeing a skunk in daylight is not necessarily an indication of rabies and should not cause undue alarm. Pay attention to the overall health and behavior of the skunk, and if it appears to be going about its business, do not disturb it and maintain a respectable distance.

Striped skunks typically have litters of 4 to 6 young born between May and June. The young stay with the female until fall, when they begin to disperse in search of their own territories and winter den sites. This behavior, known as the “fall shuffle” puts roaming skunks at risk, increasing encounters with humans, our pets, and predators. As evidence of this shuffle, notice how many road-killed skunks and raccoons you see during the fall.

Striped skunks have a very good sense of smell, and being omnivores, consume a varied diet, preferring insects and their larvae. They also consume eggs, berries and other fruits, and in winter and early spring when other food is scarce, small rodents. In late summer and fall, skunks can cause damage to lawns as they search for insect larvae, such as white grubs. The damage is distinguishable from that caused by raccoons, as the sod appears as if someone has neatly rolled it back with the intent of transplanting it elsewhere. Any control of this damage must first begin with the control of white grubs in the soil. Contact your local County Extension office or Horticulture Extension for the appropriate timing and chemicals necessary to control grubs. This feeding activity in the fall builds up fat reserves for winter. Skunks do not hibernate but will sleep for a week or two during severe winter weather.

An example of using hardware mesh under a deck to exclude wildlifeDuring the fall, skunks, as well as woodchucks, raccoons, rabbits, chipmunks, opossums, and others are all on the lookout for winter shelter. The deck or patio becomes a popular hangout for these critters, sometimes for the long run. Skunks can cause an odor problem, not to mention the damage and mess of digging. The solution is to exclude them, thus preventing access in the first place. This can be done by adding a fence below the deck, using 1/2 inch mesh hardware cloth, attaching it firmly to the deck frame and burying it 10-12 inches below ground.

Fall is also a common time when your dog or cat, if left to wander at night, may bring home the odiferous perfume of a “not-so-romantic” encounter with a skunk. What to do? The commonly suggested bath in tomato juice fails to adequately do the job and usually just make us or pets smell like tomatoes and skunk! If you, your pet, or side of your house is ever sprayed by a skunk, there is a very effective home remedy that works on almost all surfaces. The ingredients are inexpensive and commonly found around the house.

In an open container, mix together ¼ cup baking soda, a fresh 1 quart bottle of 3 percent hydrogen peroxide, and 1-2 teaspoons of liquid dish detergent. This solution must be used right away and cannot be stored. For pets and people, thoroughly work the mixture into the fur, hair, or skin, avoiding the eyes and mouth, and leave on for 5 minutes. Then rinse with fresh water and repeat if necessary.

This should eliminate the order, but avoid getting it on cloths that you don’t want bleached. Well laundered and deodorized clothing will, over time and exposure to air, lose the odor, although the garbage may be their ultimate fate way before then!

Skunks may get a bad rap for the smell, but remember to appreciate their striking pattern of black and white and their ecological role as consumers of our insect pests. And keep the hydrogen peroxide handy, just in case!

Photo Credits: Skunk damage, Iowa State University Extension and Outreach; Deck fencing exclusion, Jim Pease Iowa State University


Wildlife Crop Depredation

Producers all across the state ask this question every year: crops that were growing healthy one day can be shreaded or knocked over the next, ruining chances for a yield on small, and sometimes large scales.  Sometimes, the likely culprit is still visible, or left behind evidence of its presence like tracks or feces. But more often, the evidence is circumstantial, and producers have to diagnose the likely cause and consider options for abating the issue.  

Cover of Purdue University article on Identification of Wildlife Crop DepredatationResearchers from Purdue University extension conducted a detailed research study in a corn-bean rotation system in Northern Indiana to help provide some insights into what causes crop depredation and how to identify and diagnose the likely culprits.  Here are the key findings from that study:

  • White-tailed deer accounted for 61% of documented soybean damage but only a small percentage of documented corn damage.
  • Groundhogs accounted for 38% of soybean damage.
  • Raccoons were responsible for 87% of the documented damage to corn, with the most raccoon damage occurring during the R3 and R4 reproductive phases of development.
  • Wild turkeys, although commonly observed feeding on insects or seeds in the fields, accounted for no detectable damage to either corn or beans.

Check out the guide to Identification of Wildlife Crop Depredatation produced by the Indiana study for help diagnosing damage on your farm. There is also a website on Identification of wildlife crop depredation that's a great resource as well. 

The likely culprits on your own farm will depend a lot on what other sorts of cover is found around your fields. In the Indiana study, raccoons were really problematic because there were high raccoon densities in isolated woodlots in the middle of the crop fields.  Producers in some parts of Iowa may face similar problems, whereas in other parts of the state with fewer trees, raccoons may not be a major issue.  A study in Iowa described in our article on wild turkeys found that although many producers in Northeastern Iowa suspected turkeys were depredating crops there, little damage by turkeys was documented. Rather, turkeys were just conspicuously feeding on insects and earthworms in the crop fields. 

For help diagnosing wildlife depredation issues in your fields, check out the Iowa DNR website on wildlife damage management. There you can find an article on identifying crop damage, abatement techniques to deal with damage, information on options available to producers with deer damage, information on wild turkey crop depredation issues, and more resources on wildlife damage in Iowa.


Bats Around and in the Home

Photograph of roosting Big Brown Bats in a home.

Bats are extremely valuable in insect control and a welcome and often misunderstood part of Iowa's natural environment. We want them flying around outside gobbling mosquitoes, crop-damaging insects, and others. We just don't want to share their living space with them! Click here to learn more about Iowa's bats and the challenges they face.

Like almost all other animal species, Iowa law protects bats. While homeowners are allowed to protect their property, repellents are largely ineffective, including those expensive "sonic" or "ultrasonic" devices and the relatively inexpensive mothballs. Thus, excluding bats from buildings is the only way to deal with them. Understanding some bat habits is the key to successful exclusion.

What you need to know about the bats sharing your home

First, bats are nocturnal. They emerge from their roosts at dusk each evening, searching for food and water. Thus, exclusion activities must be done after they've emerged, NOT during the daytime. Blocking entrances during the day only guarantees more severe problems, increasing the likelihood that they will come down through the walls in search of a way out or die in the house, causing a different set of problems for the homeowner.

Second, bats follow air currents. Any spaces--say, your attic and a bedroom--that have different temperatures and are connected by a crack or hole, automatically have airflow between them. Bats simply follow those air currents. Blocking those air currents is the key to successful bat exclusion.

Third, August and September are the best time to do the exclusion. Bats are mammals and often form maternal colonies, a mother and her one or two young hanging together with dozens of other mothers and young. Since young bats are naked and blind, mothers leave them behind each night to seek food and water, returning later in the night to nurse. If exclusion is done prior to August you may only exclude the mothers and end up having the young die in your house.

Finally, only two of Iowa's nine bat species, the big brown bat and little brown bat, commonly use buildings in the summer for colonies. Only the big brown bat uses buildings in winter. It is mainly these two species that cause problems for homeowners.

Excluding bats

Wait until after August 1st to exclude bats to ensure flightless young are not orphaned inside the home.

Step 1: Find the entry points.

Finding the entrance can be a family affair. Take lawn chairs, your favorite drinks, and a flashlight and sit outside in your yard about sundown. Watch for emerging bats. Check the obvious places first: around the chimney, gable vents, or roof vents. Don't forget the not-so-obvious places also: under the eaves, behind the rain guttering, under torn shingles. All these are common entrance sites and indicate that some repair is in order. Some buildings have more than one entrance site. Any holes the size of your thumb or larger are enough for bats to find and exploit. Don't forget, many bats may use the outside of your house without posing any issues to the inside, so be sure to find likely entry points, as illustrated in this figure.

Likely entry points and external use points for bats in and around homes.

Step 2: Allow the bats out, but not back in.

Once you've identified the entry points around your home build a one way door on the outside of the house to allow the bats to crawl out of the hole, but not fly back in. A one-way door will be anchored above the hole and then hang loosely below. It can be made from half-inch mesh bird netting, screen wire, heavy cloth, or even a sock with the end cut off to create a tube around the hole.

Let's say, for example, the entrance is a crack one half inch wide and 6 inches long. Cut a piece of netting or screen. Place it over the entrance crack so that the entrance is in the upper half of the net/screen. Use duct tape to tape the top and two sides of the screen to the building, leaving the bottom edge open and just loose enough for the bats to squeeze out. Bats will emerge that evening, hit the screen, crawl around until they find the bottom loose, and then fly out. When they return, they return to where the air current is--the crack--not to the bottom of the screen. If you leave this up for 4-7 days, you can be assured that all bats are out and the repairs can be made, this time during the daylight hours.

Two alternative types of one-way doors for bats include a tunnel design and a haning door design.

Step 3: Repair the holes and entry points

Use foam sealants, fine (half inch or less) wire mesh, new boards or soffit, plaster, or any other means necessary to fill all holes in and around your home to prevent bats from finding their way in again.

For more detailed information on issues with bats around the home visit the detailed article on bats from the Prevention and Control of Wildlife Damage manual.