Otto Chrons bio photo

Otto Chrons

Jack of all trades, master of some.

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Did you know that a single bat can eat up to 3000 mosquitoes in a single night? This 100% organic mosquito killer is much more effective than the industrial solutions based on CO2 and special (expensive) odors. Now, how does one install a bat (or preferably several!) on their property to take care of those nasty little bugs?

As both our kids are big fans of nature and our son especially interested in bats, we decided to build a day-time house for the bats. They sleep during the day, you know. A bat house is quite different from your typical bird house since bats are not birds (surprise!)


To build a nice bat house, all you need is some rough cut wood (or plywood in my case), a few screws and some power tools. I happened to have a suitable piece of well-aged plywood that had been outside in the sun and rain for a couple of years, resulting in a nice rough texture and gray finish. This would do perfectly for the project and would camouflage very well on the tree.

The design of the house is simple. It has a straight back, heavily slanted roof and a 20mm high entrance at the bottom (this is really the only critical dimension of the house). Below the entrance is a flat “landing area”.

Basic structure
The main entrance

Note the shallow horizontal grooves I cut on the landing area. These are to help the bats to climb into the house. If your building material is not very rough, you might want to do additional grooves inside the house as well.

Even though the entrance seems really low, the bats are rather small creatures (unless you live in Australia and are building a house for a flying fox) and they will fit in nicely. The small entrance prevents birds from taking over.

Once all the pieces were cut, I drilled some holes to help with the screws and the kids got to try some power tools, tightening the screws. A 18V Makita runs the screws deep really quickly!


I made the roof extend beyond the top to protect the house from rain. Since the material was nicely colored to begin with, we didn’t bother painting it. If you do paint yours, remember to use non-toxic paints.

As the bottom panel is attached with two screws, it makes cleaning the bat house easy.


Even though bats are night dwellers, they really like to keep warm during the day. Therefore the bat house should be placed in an open area, facing towards the sun. It should be installed on a tree or a wall, high enough so that cats cannot jump the landing bats. In our case, it was installed on a pine tree close to the lake and our sauna. Bats like being close to the lake as there are a lot of insects to dine on.

Ready for the tenants, disguised from others

When installing on a tree, use wire or strong rope attached to an eye bolt (or similar) to prevent damage to the tree.

Now all we need is a BatCam to see if anything is going on in the BatCave! AliExpress has some interesting gadgets that might fit nicely…