Swallowtail Butterfly Incubation Habitat

Introduction: Swallowtail Butterfly Incubation Habitat

Last year, I decided to start doing some simple herb and vegetable gardening in our small back yard in NYC. One day while I was outside tending to the plants, I watched a black swallowtail butterfly flitting around, and a few days later, I saw some black worms with a white stripe in their middle eating my big dill plant. A quick check of the intarwebs told me that these were the first instar caterpillars that had hatched from the eggs my butterfly friend had laid. I watched them every day as they munched away at my dill, fascinated at how they grew and changed shape and color. I got quite attached to these little guys, and even gave them names.

One hot afternoon, after they had grown fat and juicy, and changed from their muted black and white to a brightly colored green and yellow, a wasp swooped in and stabbed poor Flash Gordon right behind his head! Horrified (and terrified of wasps), I ran into the house screaming for my boyfriend to do something. His initial reaction at my hysterics was to grab a weapon to fight off my assailant, but after realizing what was actually going on, he appeared on the back stoop with a flyswatter asking me what I wanted killed. Obviously, it was too late at that point, and poor Flash Gordon was gone.

The next day, I jury-rigged a tent over the big dill plant using whatever lumber we had in the garage and some fiberglass window screen. Then I learned another lesson: when the caterpillars are ready to enter chrysalis stage, they like to roam far away from their "host plant", and will get out of my ghetto tent pretty easily. At this point, they will get eaten by another wasp.

After another request to my beleaguered boyfriend, the heavy clay pot with my herbs and big dill plant was in our front vestibule with the last of the yellow, final instar caterpillars in tow. This one flourished, apparently living out it's chrysalis stage behind a bookcase, until the day I came out to find that velvety black swallowtail flying in my front porch.

The situation at hand was quickly fixed by opening some windows and allowing the papillon in residence access to the world. However, as it was busy transforming itself, I had been busy transforming my dill tent into a "cage" that might actually be useful.

As it turns out, my cage did last for the second wave of caterpillars to butterflies of the summer, and the final wave of caterpillars to chrysalis to my porch for the winter, then all five over-winter caterpillars hatched just this May. Hurray! But during this time, I did notice some areas that needed improvement, thus this design for a habitat that should but useful for raising caterpillars that are safe from wasps, and hatching them into beautiful black swallowtail butterflies.

Please note: the cage is just "protective custody" for the caterpillars and chrysalis, and no butterflies are held beyond a couple of hours after emerging. It takes a couple of hours for their wings to be flight worthy after they emerge, but they only have a matter of days to live. I only keep them caged until they can fly well on their own, then let them go.

Step 1: Get Some Bugs, Or, If You Plant It, They Will Come

Please keep in mind that I'm not a lepidopterist, and the information in this Instructable is a summary of articles I've read on the internet and my own, unscientific observations. You may want to look at the following websites for more information:



The Eastern Black Swallowtail butterfly is pretty much everywhere in the United States, and quite common in the East. As the name suggests, they are primarily black, and with wings open, just a bit smaller than my hand. They have yellow and blue spots that appear more like paintbrush strokes if you look at them closely, and an orange eye shaped mark on their lower hind wings.

Presumably, the butterflies feed on nectar in flowers, but I have not been fortunate enough to witness that. The only time I see them in the wild is when they are laying eggs. Nature has given these creatures the wonderful ability to be smart enough to know to lay their eggs on plants that the caterpillars will eat, once hatched, even though these plants are not particularly attractive to the butterflies as a place to either feed or roost. The links above will suggest that parsley is a primary food source, and even that they are called "Parsley Worms". From experience, I will say that I plant a lot of parsley and not had one caterpillar feeding on it.

Instead I find that from what I plant around my home, carrot is the favorite for egg laying, and dill is second. I've also moved caterpillars from one plant to the other, and they will switch food sources, so it seems like one plant is as good as another, it's just more about what the mother butterfly wants to lay eggs on (again, with the exception of parsley, which they don't seem to want to eat).

So, in order to get caterpillars, all you have to do is plant some dill. Just get 4" or 6" pots from your local home and garden store, throw in some potting soil and dill seeds (the planting kind, not the ones from the spice shelf). Also, a lot of grocery stores now sell live herb plants, so you may be able to get a plant ready to be eaten there.

Whichever method you use, make sure to plant way more than you think you will need. A couple of caterpillars can easily destroy a full grown dill plant. Just put the plants outside on a window ledge, fire escape, back yard, etc. and make sure to check it and water it every day. Be patient and keep checking, and one day you will see some ivory/white bubbles on your plants. Those are your butterfly eggs. Soon, you will see some tiny little black dots...don't brush them away because the next time you look they will be worm shaped with a white band around their middle - that's your black swallowtail caterpillar.

While waiting for a butterfly to come along and lay her eggs, you can be getting your habitat in order.

Step 2: Caterpillar Habitat: Tools and Materials

As much as I'm not a lepidopterist, I'm also not an experienced woodworker, but if you are or have the inclination to learn, you can probably build something much nicer than what I have. I've attached a SketchUp file that approximates the dimensions that I used, but of course, it's not necessary to follow it exactly. Since it only has to hold a couple of little plants, and also I didn't want to spend a lot of money trying to build a serious piece of furniture to keep outdoors and house bugs, I went with materials I either had on hand or could get cheaply. This means furring strips and nails as opposed to real lumber and screws.

Lumber - I hate to call it that - furring strips are really more like giant splinters than actual lumber. Cut as you go, not all at once, as you may have to compensate a bit here and there.

  • 1x3x55" - 8 pieces
  • 1x3x35" - 2 pieces
  • 1x3x14" - 4 pieces
  • 1x3x8" - 2 pieces
  • 1x2x14" - 14 pieces
  • 1x2x28" - 8 pieces
  • 1x2x35" - 4 pieces
  • 1x2x12" - 4 pieces
  • 1x2x39" - 1 piece
  • 2x4 scraps - 8 chunks of about 2" each

Hardware - available at Home Depot for a couple of bucks each

  • 8 small utility hinges
  • 2 "hook and staples"
  • 2 casement window locks
  • 2" nails
  • 1-1/4" nails
  • staples


  • roll of window screening (available at Home Depot, etc.)
  • paint (I just used leftover from the basement)
  • peel and stick foam weather stripping (I had some leftover from a free energy efficiency promotion)
  • sandpaper
  • 1/4" quarter round trim (not necessary, but makes it prettier)
  • wood glue
  • wood filler putty (not necessary, but may save you some splinters)

Tools - I was fortunate enough to have access to an array of power tools, but hand tools will be just fine

  • Power miter saw, circular saw, or plain old backsaw
  • Palm sander or similar
  • Staple gun
  • Finishing trim nailer or hammer and nail set
  • Tape measure
  • Screwdriver
  • Bar clamps (not necessary, but makes things easier)

Step 3: Caterpillar Habitat - Build Your Horizontal Components

Again, if you're an experienced woodworker, you may want to skip the next few steps and build to your own design, but honestly, this is just a grown-up version of the catching bugs in a mayonnaise jar that most of us did as kids. Also, since we're working with scrap wood and furring strips (or giant splinters as I like to call them), it's going to be pretty darn unlikely that we're going to be able to get anything perfectly straight or square. Just try to get it as close as possible, and when making your cuts, try to use the straightest bits for the framework, and cut off the bent stuff for scrap or the bottom slats as much as possible.

Using two 28" lengths of 1x2, two 14" lengths of 1x2, and one 14" length of 1x3, some wood glue and nails, assemble a rectangle with the 1x3 dividing it in half as shown in the picture. Try to make the outside corners as square as possible, and make it lay as flat as possible. These sticks are very small and light, so clamping them to your work surface when you nail will help a lot.

This piece will look kind of like a window when you're done. You will need to make three of these, one for the very bottom of the bug house, and two for the top.

You're going to have pots of dill sitting on the bottom shelf of your bug house, so this piece is going to be similar to the first three units you made, but with slats to hold the pots. Use two more of the 28" lengths of 1x2 for the top and bottom, two more of the 14" lengths of 1x2 for the ends, and one 14" length of 1x3 in the middle....then evenly space out 3 more 14" lengths between the middle and then end on each side of the 1x3. Again, glue, clamp and nail as you did for the other pieces.

When you have your three pieces that look like windows, and one piece with slats, then if you want, you can fill in any big gouges or splintery bits with your wood putty, then sand it smooth. As my boyfriend says, splinters are present all over nature, so you're probably not going to hurt your caterpillars if you skip this step, but in the long run, doing so makes it look a bit nicer and saves your hands when you're assembling everything.

Step 4: Caterpillar Habitat - Legs and Verticals, Attaching Horizontals

Take 2 of your long pieces of 1x3 and form them into an "L" shape. Now that you're working with the long pieces, the warps and irregularities are going to be a bit harder to avoid, so my advise is to try turning and swapping pieces until you get the best fit with as close as possible to a 45 degree corner with the least amount of gaps and warps. Once you're satisfied, glue, clamp and nail it together. You will need four of these for the four vertical uprights to the structure.

Step 5: Filling, Adjusting and Painting

At this point, you should have four horizontal pieces, three that look like windows, and one with slats, and those are going to fit into your four vertical leg pieces at various heights. I've said it before and will say it again, this is not fine furniture construction, but if there are big gaps or icky gouges and splinters, now is the time to use your wood putty to fill them in. After appropriate drying time, sand everything down as smooth as your patience will allow, and apply some primer and paint, or whatever finish coat you would like. It's much easier to do this now when things are nice and flat and in pieces than when it is all together and you have to contort to reach something. While doing this step, you will probably also want to include your two extra pieces of 1x3x35" strips, which will be the center front and center back of the caterpillar house.

Step 6: Assembly

Stack two of the "window" pieces together, and sandwich them in two of the the "L" shaped legs on your table or work surface. Even everything up so that the top of the leg pieces are flush with the top "window" piece. When you are happy that they are as square as they can get, do some glue and nails to attach ONLY THE BOTTOM window piece to the legs....this is going to the window piece that is closest to the long end of the legs. Take the very top window piece off and set it aside for later.

Now, very carefully, flip everything over and attach the other two "L" shaped legs. Everything is going to be very floppy at this point, so do your best to square it back up at every movement. With this structure laying on your work surface, take one of your 35" 1x3's and even it up with the edge of the "window" component, then glue and nail it in from the top. Then flip the whole thing 180 degrees and do the same again. Your 1x6's should roughly match up from the window component to the vertical. At each of the four corners below the top horizontal piece, you can attach one of the 2" 2x4 scraps, and just glue and nail everything together. (see photo for picture of corner blocks)

Now, take your piece with the slats...we want that butted up against the dangling 1x3's, and still as square as possible in the corners. As always, make it as straight and square as possible, then glue and nail. When that's done, add the corner blocks.

Step 7: Applying the Screen - Top and Sides

It's going to be a bit rickety, but stand your assembly upright. Choose which face is going to be the front or back, then starting at the top, wrap your roll of window screen from the top front, to the bottom back. Use a staple gun to secure everything in place. Pull everything taught, but be careful of pulling too tightly. I recommend holding the screen with a pinky finger's worth of tension, then shooting staples in middle, ends, and filling in around the edges.

Now that you have the top and back screened, do the same thing with the left and right sides. Just leave the front open for now.

Trim off the extra screen with some scissors.

Step 8: Secure the Top, Then the Bottom

With your assembly standing, you should be able to look over the top and see a bunch of staples and raw screen edges. Let's cap that off with one of those "window" pieces. Just pop it in place with some glue and nails.

We should have one more "window" piece left over, which is for the bottom. Go ahead and cover this piece in screen. At this point, we need some of those hinges, and our last window shaped horizontal piece. It's difficult to see in the photo, but I have a clamp holding the bottom "window" piece to the bottom of the slatted piece. At this point, just position two of the hinges evenly between these two pieces, pre-drill your holes, and screw on the hinges.

To keep the bottom closed, I used the smallest "hook and staple" set I could find at Home Depot. As you can see from the photo, I'm not using the staple part, just the hook and a screw. I have one on each side near the front.

Step 9: Add the Doors & Trim

As I've said in previous steps, since we're working with furring strips that are probably quite warped and uneven, it's very unlikely that the box is going to be anywhere near square. For this reason, I suggest making the doors to fit based on the measurements of the almost-complete box.

To start, measure the front center, from the very top to the bottom of the trap door in the closed position, which should be somewhere around 39 inches. Cut a piece of 1x2 to this link, paint it up, and attach it to the center front of the box. It's a bit hard to see in the photo, but it's marked with an arrow. The doors will butt up against either side of this piece.

Again, since we're probably not square, measure each piece for the doors individually, but in general for each door you will need two 1x2's about 35 inches long for the sides, two 1x2's about 12 inches long for the top and bottom, and a 1x3 about 8 inches long for the center. Nail these together to fit the openings as best as you can, then paint and staple on your screen.

Clamp the doors in place (or get some help holding them), then mark your hinge placement at the top, bottom, and middle. Pre-drill the holes to avoid splitting, and screw on the hinges.

On mine, I've used casement window locks for handles as well as fasteners. These also came from Home Depot and were about four bucks. You could also use just a plain hook and eye or a barrel-bolt type fastener. Either way, pre-drill your holes before you screw in the chosen fastener to avoid splitting the wood.

Despite my best efforts, I ended up with a little bit of a gap around the top and bottom edges of my doors. This was easily remedied with some peel and stick foam weather stripping that we had received from an energy efficiency promotion.

Obviously, trim isn't absolutely necessary, but I chose to attach some 1/2" quarter round to my doors and along each vertical on the sides. This is quite straight forward - just measure where you want it to go, cut to length, paint, and attach with finish nails. For the doors, I cut the trim at 45 degree angles to create mitered corners.

Step 10: Enjoy Your New Pets!

Keep an eye out for butterfly eggs (in the first picture) on your dill plants. When they hatch, they will be tiny little brown bugs with a white middle, and will eventually get a bit darker as they grow (second picture). Move the plant into your new cage, keep the plant watered, and watch the caterpillars grow. After a week or two, they will be about two inches long (third picture). These guys poop a lot when they're this size - thus the reason for the trap door to make cleaning easier.

At this point, they will leave their host plant and look for a place to attach - usually near the top and in a corner. they will attach to the wall or ceiling with a pad of silk at the tail end, then start bending into a hook shape. After several hours, they will shed their skin and transform into a chrysalis which may be green, gray or brown. They will be in their chrysalis state for about a week, then emerge as a butterfly. After emerging, it takes a couple of hours for the new butterfly to fully extend its wings and fly, but don't forget to open the doors and let it out after that so the cycle can start again.

At the end of the summer, you will find that the butterflies aren't emerging from their chrysalis after a week - this is normal and they will stay in this state for the rest of the winter and emerge in the spring around May.

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