Daniel Burden
Program Specialist, Value Added Agriculture
Iowa State University Extension & Outreach
Fall is the time of year when unwelcome pests look for shelter for the winter. It is a good time to check your home and outbuildings on your acreage to discourage pests from taking up residence.
Bats
These peaceful little insect eaters occasionally end up in our homes. They are very delicate and beneficial animals. If they are loose in your living space and are not pursued, if the lights are on, they usually will try to hide behind something. If you wear gloves there is little chance that they can bite you. Bats like almost all other wildlife can carry rabies, but this threat is grossly overrated. Dimming the lights will help to calm them. Try to get the little guy into a shoe box and take it outdoors. It is even easier to dim the lights, open up the doors and let the bat find its way out. They are quite good at this.
If you get the occasional visitor try to find where are entering your dwelling and take care of the problem by barring the entrance with steel mesh or similar material. Fireplace chimneys that do not have some sort of screen or liner are good candidates for entry and roost space. So too are old casement windows, especially if they have been not so well retrofitted and the new inserts have gaps in the fit. It only takes one of these, since most species of bats only need one-quarter-inch of vertical clearance to squeeze through a gap.
Bat colonies can be a more serious problem. There are times of the year when they scrabble around in walls finding favorable temperature zones and colonies produce urine, guano and the occasional dead individual. In some old structures, these things have built up to astonishing levels and can eventually bleed through plaster or if combined with a roof leak, create a rather nasty mess.
Colonies are best dealt with by an exterminator (who should work to humanely exclude the bats rather than kill them); but the enterprising home owner can, thanks to any number of good extension publications, build a simple one-way excluder to help the colony to “out itself.”
This is done by finding where the animals enter and leave the dwelling, then fitting the opening with a piece of PVC pipe or dryer-vent tubing to which a soft sock-like extension has been fitted. The bats can easily leave by going down the tube and out the soft attachment, but coming is to closed attachment flap is impossible. Once one is sure the colony is out of the building, and this can happen the first night they leave, then simply remove the excluder and close the opening. It is most humane to use an excluder at times of the season when there are no baby bats that could be left behind and stranded in the structure. Once they are old enough to fly you (and they) are good to go!
Snakes
These creatures usually are a problem in hot weather when a cool garage or shaded woodpile makes and inviting retreat. Since snakes are cold-blooded reptiles, they are going to show a preference for these types of places. Conversely, it is cold outside, they may want to find a little warmer place in which to hibernate or catch a few rays to warm up. Snakes are unlikely to be in places that are openly exposed since they are a quite susceptible to avian predation by hawks, and other birds of prey.
When encountered, usually they surprise us more than we surprise them, but all snakes will react defensively to being surprised, usually this will result in the snake coiling and perhaps hissing and showing its open mouth. If provoked, most species will bite. Some snakes, like the placid Eastern Hognose, a toad hunter by profession, will exhibit a behavior called “thanotosis,” also known as “playing dead.” These guys will straighten out and rollover on their backs, belly up. It can be quite a bit of fun to roll them right side up and watch them roll back over; hardly a convincing dead-animal act.
In most of the United States, most commonly encountered snakes that are found around human habitation are non-poisonous, but in the South, West and parts of the East, it is not uncommon to find poisonous snakes around buildings in somewhat sheltered areas (flower gardens, porch overhangs, garages and carports). In one instance, a homeowner living on a wildlife-friendly acreage in Wisconsin regularly found harmless garter snakes in the sump-pump pit of his split-level home. A careful search for their point of entry found an unsealed gap around an incoming water pipe. Once the snake entered the dwelling, it encountered the basement wall in its attempt to find a way out of the building; this of course resulted in it eventually ending up at the partly covered sump pit, a perfect snake trap.
This presents a good insight into a way to manage the inadvertent trespassing. Constructing low “snake fences” outside barriers that route the critters around your dwelling is a good way to keep them from your yard, car port, children’s play area or dog kennels. Most snakes can climb but unless they have a reason to do so, usually will be on the ground, most of time when encountering a barrier, they simply follow along it, after all, there could be a mouse nest along it. Which brings us to the subject of birds and rodents; many snake species regularly eat them. If you home has bird feeders for example, they will also attract rodents, and the rodents may attract snakes. Bird feeders are great, but one may want to locate them a distance from the house, or simply make sure that they are over open ground where there is no adjacent predator-friendly cover like bushes, brush or wood piles. Snakes usually will retreat most of the day under some sort of cover. Any sheet-like material; old tarps, discarded plywood, vehicle parts, can be perceived by a snake as a nice safe place to nap, digest a recent meal or get out of the heat or cold. These habitats are also attractive to rodents, again, attractive snake food. Keeping the yard of your farm, ranch or home free of material waste clutter will keep down your potential critter apartments and potential infestations of unwanted critters.
If in doubt to the identification of the snake do not under any circumstances handle it. Call someone with more snake experience or your local wildlife control professional. Needlessly killing a snake out of fear or loathing is little to brag about, the creatures are really quite defenseless against humans, especially if they are cold and slow, and many species are endangered and could be quite rare. They also are interesting animals; some are quite attractive and beneficial with respect to the slugs, rats, mice and even other less-desirable snakes that may show up on your property.
Mice and similar Rodents
No mystery here, when it comes to keeping out these critters, gap sealing and hygiene are two important steps. Bird seed, food waste and pet food are extremely attractive to rodents, particularly rats, mice, chipmunks and other ground squirrels. Keep your bulk feed in sealed containers, move the bird feeders away from the dwelling, and you’re your animals in a structure or substructure that cannot be accessed by a rodent. This can be as simple as a plastic storage tub whose walls are low enough so that the cat can hop in or the dog can reach over to access the chow line, but the smooth and slippery barrier is too much for the rodent. If you think the plastic is not slippery enough some household or automotive silicone spray will do the trick. Gap sealing is extremely important. One rodents find a gap in a structure they frequently cause greater damage by enlarging it. A great solution is to get a can of expanding-epoxy boat-floatation or house insulation foam. Pack the gap with a wad of scrap wire mesh, then seal it with the foam. Rodent teeth are impressive, but don’t work so well on steel wire in acrylic resin.
Of course sticky-barrier, live and snap traps are very effective control devices, just be sure to place them where children, pets or desirable wildlife will not be exposed to them. It is always a good idea to place any type of trap inside a small structure or under concealing cover that is attractive to the target animal and less so to the innocent passerby!
Other Resources
There are many resources on this subject. Here are few good ones!
- Home, garden, turf, and landscape pests. University of California's official guidelines for managing pests with environmentally sound methods.
- Montana Vertebrate Pest Program
- Principles of Vertebrate Pest Management. Washington State University Snohomish County Extension
- The Vertebrate Pest Control Handbook Online