Last year the mosquito population was really bad. Several of the neighbors bought those expensive propane mosquito control devices. They do kill mosquitos - but not nearly enough to make a big difference in my experience, and besides they have an ongoing expense with all the propane refills. As is usually the case, nature's controls can work a lot better!
A single bat can eat between 500-1000 mosquitos in ONE HOUR (more than one of those propane contraptions gets in a week). If you've got a bat house packed full of bats, you can multiply that number by 100 or 200. Nothing compares to the efficiency of the bat at destroying annoying insects.
So anyway I knew I had bats in my area, because you can see them buzzing around in the sky during the Summer. But I've also heard stories from people that put up houses and never got any bats to move in. In fact there are some bat houses at a local park that seem to be in a great location, but they've never had bats in them. This was obviously going to require more research. Thankfully I was able to find quite a lot of information on the internet. It turns out that bats can be very particular about what type of bat house they will move into, and if you just meet most of the suggestions and you live in an area that has bats, you are almost guaranteed to be successful. You can take a look at the research results here. Here's an additional document from Bat Conservation International: Criteria for Successful Bat Houses. In a nutshell, here are the tips for greatest success:
After all of these considerations it became obvious to me why most of the bat houses I've seen have been unsuccessful. Many are simply too small, and mounted in poor locations.
I scoured the net for good bat house plans, and decided to use the large nursery box plans found on the Maryland department of natural resources website. I can confirm that this is an excellent design. Here's a snapshot of the finished product:
For best results, you need to put the house up before the time of year when the bats are scouting for new roosting sites for the following Spring. They do this during the Fall as they begin to head back to the caves for winter hibernation. But it doesn't hurt to put it up during the Summer so they have even more time to find it - they will be back next Spring and will know right where to go!
If you are planning to build a house you should also consider alternative materials. Houses have been made from plastic and large PVC pipe, metal, etc. Just search the internet and make sure you go with a proven successful design. I put regular roofing shingles on top of my bat house and painted everything with a quality exterior paint to protect it for many years but other materials could last even longer and require less maintenance. You should also consider purchasing a bat house instead of building it yourself - ASSUMING you can find one that meets the criteria for success. The time and expense of building your own can be considerable.
At any rate, Spring is finally here, less than one year after putting up the bat house, time to take a look inside:
WOW - YES - WE HAVE BATS!!
OK - so its only two, but that's a good start. Can't come soon enough as far as I'm concerned, because the mosquitos and gnats have been pretty bad so far this year. But I've noticed a big improvement already since the bats have arrived! Coincidence? I think not.
And just to dispel some urban legends - bats will not fly into your hair, the term "blind as a bat" is a misnomer, they actually have pretty good eye sight in addition to their use of echolocation to navigate in the dark. Also their rabies incidence is low - matching that of other wild animals. Obviously you should never go near a bat, especially one on the ground or out during the day as it could be sick. There is little risk however, and the rewards are great. Bats protect us from numerous mosquito born illnesses such as west nile virus, there are three forms of encephalitis virii found across the U.S. transmitted by mosquitoes (in other countries mosquitoes carry dengue, yellow fever, and malaria). Mosquitoes spread so much disease, sickening hundreds of millions of people a year, that they are often called the planet's deadliest creature. According to the CDC, each year 350 to 500 million cases of malaria occur worldwide, resulting in over one million deaths. It seems every few years we learn about some new ailment carried by mosquitos (for example they even carry the bacteria that causes Lymes disease although there is little evidence yet to suggest they transmit it).
In the very least, having the bats around allows more people to go outside without putting toxic chemicals on their skin for protection from mosquito bites. The bats also prey on other harmful bugs such as moths and beetles which can damage our garden plants and trees. They also pollinate certain crops and trees. All in all, they help keep nature in healthy balance.