Bats are opportunistic feeders meaning that they eat all kinds of insects. This includes flies, mosquitoes, moths, beetles, and other insects that damage garden plants and crops. North American bats are nocturnal creatures meaning that they sleep during the day and feast on insects during the night.
Bats are much more effective than birds at clearing away insects. While many insects can hide from the birds in the darkness of the evenings, they cannot hide from bats because bats make use of echolocation to easily track their insect prey.
When a colony of bats moves into a bat house most insects will flee the area and most of those that remain will be eaten. Bats eat over a third of their body weight in insects every night, and so if you have a strong colony of bats on your property you should expect a significant reduction in the number of insects in your area.
The most effective way of reducing the mosquito population is to eliminate their ability to breed in stagnant water; so everyone should do their part in removing buckets, birdbaths, old tires, or anything else than might hold water. Despite these efforts, in natural wetland areas the emptying of water containers will not be enough to stop mosquitoes from breeding.
In regions surrounded by lakes and swamps mosquitoes will often multiply out of control. Besides making outdoor activities unpleasant, an abundance of mosquitoes can be a health risk since some mosquitoes are carriers of the West Nile virus or other diseases.
Opinions differ as to whether it is better to use insecticides or organic means for controlling these flying mosquitoes. Most people who are successful in attracting a colony of bats to their property will swear by their effectiveness in keeping the mosquito population under control.
Likewise, the National Parks Service and nearly all state wildlife agencies agree that bats are effective in reducing mosquito populations. Canadian Federation Wildlife not only recommends attracting bats for controlling mosquitoes but they actually give away small bat houses to any organization that ask for one. Yet nearly every local mosquito - control government agency is on the other side of this debate.
A lack of patience may be the reason why authorities disagree on what is the best way of controlling mosquitoes. It can be a year or two from the time a bat house is placed on a property to when the colony of bats is numerous enough to be effective in reducing the mosquito population. Most people do not have this much patience.
When the mosquitoes are biting many people demand that their local authorities do something right away. So in response, the local government officials will order the spraying of insecticides. The spraying of insecticides is one of the least effective means of controlling mosquitoes. Besides killing the mosquitoes, the repetitive spraying of insecticides also kills bees, bats, fish, and numerous other animals: including humans. These sprayed insecticides are almost always a greater health risk to humans than the diseases carried by the mosquitoes.
Bats are the healthy, environmentally friendly means of controlling insect pests. Once bats take up residence in your bat house they will keep returning every spring. And while you're bats will not eliminate all of the mosquitoes, they will keep the mosquitoes and other insect pests under control. Think of a bat house as your organic, maintenance free pest control system.
Just because you place a bat house on your property does not guarantee that a colony of bats will take up residence in your bat house. And what point is there in having a bat house that is never used by bats?
Based on several factors, your odds of attracting bats will vary between zero to about ninety percent probability that you will have bats within two years. It comes down to this, if you do everything right you will more than likely have bats within the first year, whereas the people that cut corners are just wasting their time.
There are three main factors determining the success of your bat house: proximity to water, where or how the bat house is mounted, and the quality of the bat house.
Proximity to water:
For sustaining a large colony of bats it is best if the bat house is within a quarter mile from a source of water such as a lake or stream. Beyond a half mile it is still possible to attract a few bachelor bats but the likelihood of attracting a larger nursery colony is slim.
Most insects also like to be in close proximity to water and so it often happens that insect pests overrun lake lots and other properties in close proximity to water. Placing a bat house on these properties provides a steady food and water supply for the bats that bring balance back to the environment. Thus riverfront properties, lake lots, and golf courses having numerous ponds are often ideal locations for bat houses.
Where or how the bat house is mounted:
A bat house needs to be located either high on a south or south-east facing wall or mounted at the top of a fifteen foot pole. It should never be placed on the trunk of a shade tree.
A few things need to be considered when deciding where to locate your bat house. For several reasons, it needs to be out in the open and away from tree branches. Bats locate new homes by sight so if it is hidden they may not see it. Bats prefer that the interior temperature of the bat house stays between 80 F and 104 F, and so the bat house should be placed where it receives the full warmth of the sun. Protection from predators is another reason why tree branches should be kept at least twenty feet away from the bat house. This can reduce the possibility of owls or hawks ambushing the bats as they leave their bat house. If placing a bat house on a pole, consider mounting two bat houses back to back on the pole since this will better moderate the temperature in both bat houses so that the temperature stays within the range that the bats prefer.
The quality of the bat house:
Poorly made bat houses do not attract bats. Remember, it is critical that all of the requirements are fulfilled to assure your best chances of achieving success.
Bat Conservation International is by far the largest and most respected organization involved with the conservation of bats. They have a ten point certification program that assures that the inspected certified bat house fulfills their standards. The criteria used for determining what constitutes a quality built bat house are based on decades of field research.
Unless you reside in certain warm areas of southwest United States, you will need to prime and paint your bat house before you mount it. The color or more accurately the darkness of the bat house’s exterior is important because this determines the interior temperature of the bat house. Bats will not take up residence in the bat house if its interior temperature is either too hot or too cold. The darker the color the more heat the bat house will absorb. Bat houses located in the cooler climates need to be painted black so that their interior stays warm. For most of the rest of the USA a dark shade is recommended. Please see the map for guidance on whether your bat house should be a light shade, a dark shade, or black. The Bat Conservation Organization recommends that you do not use oil based products since these products may be toxic to the bats. Use only a water-based primer and a water-based (latex) exterior paint and apply these coating only to the exterior of the bat house. Do not paint the landing pad area at the bottom of the bat house or any other part of the interior. To extend the life of the bat house cover the roof with sheet metal or roofing shingles.
Contracting rabies from bats is possible but exceptionally rare. For those that use the common sense of not handling wild bats with bare hands, the danger from bats is much more imagined than real. Deaths from bat transmitted rabies are far less common than being bit by a rabid domestic dog or cat, and all of these cases combined are far less of a lethal danger than either being struck by lightning or having an allergic reaction to a bee sting.
Bats are not pets. One should assume that all small wild mammals such as bats, mice, or rats have the potential of carrying rabies and other fatal diseases, and so it is unwise to handle any of these wild animals with your bare hands. Children should be warned that a bat on the ground is likely sick and so it must be avoided.
Bats will not take up residence in a bat house if wasps move into the bat house ahead of them. A bat house with a three quarter inch spacing usually do not have problems with wasps since wasps usually will not make a nest in this small space. But just to be sure it is not a bad idea to make a quick visual inspection of your bat house about once a week to make sure that you do not have any unwanted guest interfering with the arrival of your bat
A bat house requires very little maintenance. During the winter, while the bats are away, pick a relatively warm day to inspect for wasp or mud dauber nests and clear them from the bat house if any exist. About every ten years the bat house will probably need to be caulked and repainted. That is about all there is to it. As long as the bat house remains in good condition, the bats will return year after year. This is a win / win situation. You have provided these wonderful animals with a much needed home while they clear the majority of the pesky insects away from your property.