Sometimes called a hibernation box, butterfly houses are simple, inexpensive, and attractive shelters for critters in your garden. Here’s how to build one for about $3.

The butterfly house mounted over the butterfly garden

Part of maintaining an organic and sustainable garden is attracting insects who do the important work of pollination. Bees are an obvious go-to, and the European honey and the native carpenter and mason bees are both common sights here. Less common, but far more colorful, are the many different types of butterflies native to the area (with the exception of the Monarch, pretty much all the butterflies here in San Diego live throughout North America).

We plant a variety of flowers and herbs to attract butterflies and even have a dedicated butterfly garden filled with their favorite foods, but I never gave any thought to where butterflies go when they need shelter, so when my wife showed me something called a “butterfly house” that’s supposed to give them cover from birds and other predators, I was intrigued.

A butterfly house, also known as a hibernation box or insect shelter, is basically a tall, narrow box with slots insects can get in, but birds, bats and larger animals can’t. From what I read, it’s actually not particularly good at attracting butterflies (they prefer the canopy of trees and leafy shrubs), but I read the same thing about Insect Hotels, and the one I built has been quite popular with the local critter crowd. So, I figured, “what the heck, I’ll make one.”

Digging around for instructions on the Internet, I found that a pre-built box can cost $30 or more, but if you build one yourself, it’ll cost only a tiny fraction of that — like $3 and change. Better yet, you can put it together with nothing more than a drill, a hand saw and a hammer in just a couple hours. Here’s how:

Supplies

  • 1 – 5½-in. x 72-in. unfinished cedar fence board
  • 4 – 1¼-in. wood screws
  • 1½-in. finish nails
  • Wood glue

Instructions

Instructions for a flat roof and peaked roof butterfly house

There are two versions of the butterfly house, one with a flat roof, and the other with a peaked roof. The flat roof is a little easier to build; the peaked roof a little fancier. They both use the same amount of wood, so it’s entirely up to you which one you want to do.

Step 1 – Cut your pieces

Make the following cuts from your cedar fence board:

For the Flat Roof version

  • 4 – 14-in. long (these will be the front, back and sides)
  • 1 – 4½-in. long (for the bottom)
  • 1 – 8-in. long (for the top)

For the Peaked Roof version

  • 2 – 14-in. long (front and back)
  • 2 – 11¼-in. long (the sides)
  • 1 – 4½-in. long (for the bottom)
  • 1 – 6-in. long (half the roof)
  • 1 – 5½-in. long (the other half of the roof)
Step 2 – Trim your side boards and bottom

Once you have the main pieces cut, you need to trim 1-in. off width of the sides and bottom pieces. For the sides of the Flat Roof, that’s two of the 14-in. long pieces; for the peaked roof it’s the the two 11¼-in. pieces.

Trim the edge of the side boards and bottom

(Step 2a – For the Peaked Roof only)

On your front and back pieces, mark the top vertical center of the board (at 2¾-in.), then draw a line horizontally 11¼-in. up from the bottom. Using a straight edge, draw a line from the top center to both edges of the board where you made the horizontal line.

Trim the front and back boards to make the peaked roof

Use a saw to cut off the corners of the board to make your roof peaks.

Step 3 – Cut your slots in the front piece

Mark the location of where your slots will go on the front piece. They need to be at least 4-in. long and no wider than ½-in. (I used a 3/8-in. drill bit to size the holes).

Marking where the slotted openings will go on the front

It doesn’t really matter how many slots — 2 to 4 is fine — bugs aren’t picky, just as long as they’ve got enough enclosed space to hide.

Using your drill, drill a hole at the top and the bottom of where your slots will go. Then, using a hacksaw, jig or coping saw, cut the slots out between the holes.

Step 4 – Build the box

The sides are cut to fit inside the front and back pieces. Run a bead of glue along the edge of a side piece, align it with the bottom of the front piece, and nail it together with a few finish nails. Repeat for the back piece and the other side.

Butterfly house assembly – side view

Once you’ve got the four pieces nailed together, add a little glue to the edge of the bottom piece, slide it in place and tack it in place with a few more finish nails.

The box with the four sides and bottom

Step 5 – Add the roof

You’ll be screwing, but not gluing the roof on the box. This is so you can remove the top and clean the box out every so often.

Closeup of butterfly house roof(s)

For the Flat Roof version
Align the front and back of your roof piece on the box. Then, using a tape measure, slide the roof over until you have a 1¾-in. overhang on both sides.

Using your wood screws, screw the roof to the top of the box.

For the Peaked Roof version
Align the shorter roof piece (the 5½-in. piece) with the top of the roof peak. Screw one wood screw into both sides to hold it in place.

Now take the longer roof piece and align the long edge (the 6” one) of the board so it overlaps the shorter roof piece you just attached to the top (see the illustration).

Use your other two screws to attach this half of the roof.

Butterfly house with the roof

Step 6 – Decorate (if you want to)

You can leave the wood unfinished and let it weather naturally, or, if you’re so inclined, paint the outside. Either way, leave the inside unfinished.

My wife felt it was too bland as bare wood, so I made the roof barn red and painted the rest a murky sage green to match our house trim.

The butterfly house after painting

When she felt it was still too bland,she gave me a metal butterfly ornament she picked up at the dollar store and had me attach it to the front (you know, so the butterflies would know the house is for them).

Step 7 – Mount

The butterfly house complete with decorative butterfly

You can mount the butterfly house on a pole or beam. It just needs to be at least 4 feet off the ground. A shady or lightly covered area with water and/or a food source nearby is preferable, as those will draw the butterflies and make the house more likely to be found.

I mounted mine using an “L” bracket and a zip tie on a pole that’s surrounded by a small guava and overlooks a portion of the butterfly and tropical gardens.

Is it working?

In the week that it’s been up, I’ve seen a couple of butterflies near it (a morning cloak today!), but so far, no takers on the free housing — at least as far as I can tell.

No worries, there’s a whole summer and an autumn still ahead, so I think the chances are good that we’ll get residents of one sort or another before winter arrives.

Fingers crossed!