Raising Giant Silk Moths

When I was a kid, I found a HUGE green caterpillar in the backyard that looked like it had ladybugs growing out of its back. I used my insect book to identify it, and found that it was the larvae of the giant Cecropia moth. The species of silk moth will spend all winter in a cocoon and hatch in the spring, boasting a wingspan of 6 inches, give or take.

Very excited by this find, I housed the caterpillar in a roomy hamster cage, fed him, and kept the subsequent cocoon safe all winter. I was very disappointed one spring morning when I went out to my treehouse to check on the cocoon and found the moth had already hatched...and slipped through the hamster cage bars and flown away before I could ever see it.

Fast forward 20+ years to me browsing eBay, doing what most adults do; try to buy back their childhoods. I discovered a silk moth supplier in Arizona who sold the wintering Cecropia moth cocoons (shipping to CA was legal--I made sure to ask). After some consideration and research, I decided to build a "moth house" so I could finally see a Cecropia in person. This structure would also allow me to facilitate the adult moths' breeding instincts and the raising of any caterpillars to come.

This Ible focuses on the needs of Cecropia moths in particular, though the build will also be relevant to other silk moths (Lunas are what I'd like to try next) and the raising of your local butterflies. I'll be focusing on function as well as optimal quality of life for the insects within.

Why raise giant moths? My goal is to successfully breed caterpillars that can be given to community members and classrooms for educational purposes, as well as obtain adult specimens for entomological display.

My initial sketch was for a different size than the final house, but the materials and principles remained the same.

PVC pipe for a lightweight frame structure that could be easily disassembled for transport if needed.

2 screen mesh walls for ample air and temperature circulation, easy cocoon attachment, and footing for the adult moths.

2 all weather tarp walls to provide shade and rain protection.

All weather tarp roof panel to provide shade, rain protection, and to block the moths from the view of predatory birds above.

The bottom will remain open for easy cleaning and so potted host plants can be slid underneath for inclusion in the habitat.

Wide tabs of tarp will be attached to the base to serve as anchor points, weighted with heavy garden objects.

Host plant --Either available in nature locally or purchased from a garden center. Avoid gathering foliage from places where pesticides are likely to have ben sprayed, such as golf courses.

1/2 inch PVC Pipe Lengths -- These make up the frame of the moth house. You can make this any size you like. For my balcony-friendly version, I went with (4) five foot pieces and (8) 1 foot pieces. Most hardware stores will sell PVC in longer lengths like 10ft. If you ask nicely, most places will take your purchase in the back and cut it down to your preferred sizes for you, making it much easier to cart home.

1/2 PVC 3-Way Elbows -- These will be the corner pieces that bring your frame together. Try to find elbows that have "slip" ports on all three openings.

1/2 inch PVC male adaptors-- If you can only find elbows that have a threaded port involved, you may need "male adaptor" pieces to convert the offending side into a slip. My elbows had 2 slip and 1 threaded, which ultimately meant my moth house was slightly rectangular (function was not affected).

1 Roll Fiberglass Window Screen -- Can be found in the doors and windows dept. at your hardware store.

1 Weather Resistant Tarp -- inexpensive and easily found at hardware stores. They come in a variety of sizes, so find the smallest tarp that will accommodate your moth house dimensions.

1 Roll Velcro --regular or self adhesive

E-6000 or other flexible permanent adhesive. I used Loc-Tite on my base anchor tabs since I feel more confident in its ability to withstand moisture.

Tools:

Sewing Machine

Rotary Cutter and Self Healing Cutting Mat

Stick Pins

Scissors

Safety Pins

Residents:

Ideally these would be found locally, in nature, or you can order from a reputable supplier.

A responsible seller will be aware of state law and any other limitations on where they can ship. There are some non-native species of butterfly I can not receive in California, due to the caterpillars being a pest concern. Suppliers should be willing and able to address any questions you have that are not already verbalized on their website.

**Order Responsibly. Never take on more than you can properly feed or house. Never release a non-native species of insect into the wild.

Before you purchase or hunt for caterpillars, the responsible thing to do is make sure you'll be able to meet their dietary needs. Research your caterpillar of choice and find out what their preferred host plants are. Cecropia caterpillar feed on maple, cherry, plum, apple, box elder, willow, lilac, and a few others.

If you live in an area with plentiful trees, you may be able to identify a large, continuous source of food for your caterpillar. When I was a kid we had a maple tree, so I would gather fresh leaves every day and put them in the container with the caterpillar. Always provide fresh foliage daily and err on the side of providing extra. You don't want a very hungry caterpillar to run out of food while you're at school/ work.

Since I now live in urban Los Angeles and the Cecropia's host plants are not as easily found, I decided to purchase a plant well in advance to give it time to grow before any caterpillars would need it. I bought a climbing species of lilac which, trained to a rod or tomato cage, will make a nice vertically formatted plant to fit inside the moth house.

I have read that caterpillars tend to choose one type of plant early on and then prefer to eat that type of leaf the rest of their cycle. So, again, make sure you have enough of one type of host plant to get caterpillars through. You might be able to offer a variety of plants, but whichever one they tasted first is probably going to be their go-to.

Work somewhere with plenty of space to lay out and manipulate your PVC. Normally I would have gone outside but it was 90 something degrees that day and I opted for a stretch of living room floor instead.

You'll begin by building the base footprint of the structure.

Lay out your 3 way elbows, facing each other to map out a square. As mentioned previously, threaded ports will require male adapter pieces to make the elbows work with your PVC lengths. Adapters simply screw in place on the threading. You can see in the 6th photo how the addition of adapters makes my base rectangular, which is totally fine as long as your top mirrors this shape.

Connect the elbows using (4) one foot pieces of PVC. Press the resulting shape flat to the ground to ensure all connections are firm and squarely situated on the ground plain.

Insert your 4 long pieces of PVC in the vertical ports of your elbow joints. This gives you the ultimate height of your moth house. It is important that this habitat be generous in size, allowing moths to flutter up and down without damaging their wings on the structure.

Connect your remaining elbows and one foot PVC lengths in the same manner you used to create the base.

When finished, you will install this upside down; fitting the top of your tall PVC pipes into the vertical ports of the elbows. This caps off the structure, giving you a lightweight but sturdy frame.

2 sides of the moth house will be screen. This will allow healthy fresh air flow, temperature regulation, and provide the moths with a surface they can easily climb.

Unroll your fiberglass window screen and flatten on the ground.

Lay the PVC frame on its side on top of the screen, lining up the edge and corner squarely. Push the PVC frame in 1 inch from the edge to give yourself some seam allowance.

Wrap the screen up and over so that it covers a second side of the frame. Take care not to let the frame shift positions while you work. I could not find a reliable way of marking measurements on the screen, so keeping edges and corners lined up was key.

Since I could not make markings on the screen, I used a ruler to measure the excess screen (the distance from the edge of the roll to the point on the frame I wanted the screen to end) so I knew how much to trim away.

Place a cutting mat underneath the end of your screen roll. Using a ruler and rotary cutter, trim away the excess inches of screen you just identified.

Work vertically, trimming all the way up the length of your frame.

When you reach the top of your frame, scoot the cutting mat over and work horizontally. Trim away all excess screen 1 inch above the top of your frame. Again, we're leaving that extra inch for seam allowance. You can move the PVC frame out of the way while you work, just make sure you keep cutting in a straight line and don't veer up or down.

This will leave you with a piece of screen that covers 2 sides of your moth house frame.

Place your frame back on top of the screen piece, as it was when you first started. The PVC will serve as guidelines so you can cut door flaps that are reasonably centered.

DOOR CUTTING: You will make 3 door flaps; 1 high, 1 low, and 1 in the middle. This will ensure you can easily access any part of the moth house for maintenance and care.

Slide your cutting mat underneath the screen, near the top of the frame.

Find a rectangular template to trace with your rotary cutter for easy, consistent door making. We get a ton of junk mail from Omaha Steaks and this plastic card was a great size. A good door flap will be large enough to comfortably fit your hand through, as you will need to be able to access the inside of the house to provide food and do cleaning.

Place the template on your screen. Use the guidelines on the mat to situate it squarely.

Make 3 cuts: Left side, Right Side, and Bottom. Leave the top edge attached!

Slide your cutting mat down and repeat all door cutting steps toward the middle of your screen side.

Slide down again and repeat toward the bottom of the screen side.

Since you've already determined how much material it takes to cover 2 sides of the frame, making your tarp half is easy.

Spread your weather proof tarp out flat on the ground.

Place your finished screen piece on top, living up the corner and edges squarely.

Using stick pins, pin the screen and tarp together just as you would fabric. This will keep the screen in place and ensure you get a mirror image out of your tarp.

Do a quick trace around the edge of the screen using a dark Sharpie.

Now, leaving the screen pinned in place, stand your frame upright with the edge of the pipe touching to top border of your tarp tracing. See 4th photo.

Trace around the base of the frame. This addition to your tarp pattern will be the piece that serves as your roof.

Remove your frame and remove the pins from your screen. You can set these elements aside for now.

Use scissors to cut along the Sharpie lines on the tarp. LEAVE the roof piece ATTACHED to the larger tarp tracing. You want to end up with something that looks like the 7th photo.

ANCHOR TABS:

Since this structure is lightweight, I though it would be a good idea to install some anchor points to keep to from being blown over in the wind or otherwise knocked around. The simplest solution that would work on any surface was tabs of tarp that could then be weighted down with cinder block, heavy potted plants, etc.

Cut a piece out of your excess tarp that measures approx. 13 x 16 inches.

Fold in half to form a long rectangle, then cut on that fold to divide the piece in 2.

Stand your PVC frame upright.

Slide one tarp tab underneath the base.

Fold up and over the PVC until the 2 ends meet. This will be the final length of your anchor tab. If you do not feel this is enough space to place an adequate weight on, cut a longer piece of tarp from your scrap and try again.

When you have a tab size you are satisfied with, use a waterproof adhesive like Loc-Tite to secure the tab halves together. Draw lines of adhesive on one side and then fold over and press. DO NOT apply adhesive to the PVC pipe itself. You want these tabs to be able to slide up and down the pipe so you can adjust their placement based on your installation environment.

Let the adhesive dry for a minimum of 20 minutes. Thick tarp material may tend to curl up if not pressed, so I suggest stacking some books on top while the bond dries.

You'll sew your screen and tarp pieces together just as you would any other sewing machine project. My Janome machine had no trouble getting through these unusual materials on a tension setting of 3, with a regular needle. If you're nervous about what your machine can handle, you may consider swapping out for a heavy duty needle.

Pin the edge of the roof piece to the edge of the adjacent tarp side.

Run through your sewing machine as normal, taking care to remove pins as you go and avoiding any metal grommets that remain in your tarp.

Pin the remaining roof piece edge to the neighboring screen edges. Sew again.

You'll see your piece beginning to take shape now that the roof is attached and corners have formed.

Now pin the long, vertical sides of tarp/ screen together. Run through the machine, again taking care to work around metal grommets that could damage your needle. This part takes a while simply because of the area you have to cover. If the weight of the screen/ tarp is making sewing difficult, consider pulling a side table up along your work station to support the excess while you work.

Leave the bottom (the end without the roof panel) OPEN.

Place the open end on the top of the frame and slide it on like a sock. If you encounter any resistance, check for tarp or screen that may be hung up on one of the elbows. Work down the length of the frame carefully and deliberately to avoid popping any seams or creating tears.

Since your cover dimensions were based directly off the frame, plus a little seam allowance, it should be a pretty good fit --not too tight, not too loose.

Now that the structure of the moth house is intact, it's time to finish off the door flaps so that they are escape/ intruder proof.

Using your handy door flap template again, measure and trace 3 rectangles that are 1 inch bigger on each side and 1 inch taller than your original.

Cut out the rectangles.

Next, apply E-6000 or Loc-Tite to the outside of the screen doorflaps. Hit all the edges and make diagonal lines through the middle to get good coverage.

Line up the top edge of 1 tarp rectangle with the top attached edge of the door flap. Press and adhere the two together. Allow adequate dry time before disturbing the door flaps again.

The generous overlap provided by the tarp pieces will help create a secure seal that keeps moths and caterpillars inside, and pest or predatory insects, like wasps, out.

Velcro closures will make these doors simple to use. I had heavy duty stuff laying around, but you can use regular craft weight velcro if that's what you have handy.

Take a length of velcro and sandwich the soft and prickly sides together. Doing this before you cut ensures you will always get equal and proper amounts of each.

Use your door flap template to mark and cut velcro pieces for each side and the bottom edge. Since my velcro was very wide, I was able to split my cuts in half to get more pieces made.

Keep your velcro pieces sandwiched as you attach your velcro pieces to the screen around each door frame. This will ensure your velcro halves are properly aligned to eachother in the end.

I recommend attaching the prickly side to the screen. This way if your velcro ever gets misaligned during use, only the soft side will touch your fiberglass screen and no damage can possibly be done.

If you have trustworthy self adhesive velcro, peel of the backing and stick in place. Otherwise, apply a few lines of E-6000 to secure the velcro to the screen.

Allow adequate dry time for this first side to bond.

When the first round of velcro is dry, you can remove the backing or apply adhesive to the remaining velcro backsides.

Press the tarp door down on top of this velcro and allow to dry. I turned the moth house on its side to encourage even, flat drying of the adhesive.

Use gentle encouragement at the bottom edge to open door flaps, and gentle pressing to close them. You never have to have a complete seal all the way around to consider them "closed", just enough velcro contact on the 3 sides to keep insects from passing through.

If your tarp sections have any metal grommets, spot patch the open ports with a small square of duct tape. Again, we want to shut out predatory or problem insects like wasps, and safely contain any caterpillars we may house in this later.

An ideal outdoor location is one that will not be too windy, and one that can warm and cool naturally throughout the day (not inside a shed or other situation where heat can be trapped). Do not worry if the location gets cool at night. The cocoons are made to withstand full midwestern winters and will not suffer if it gets a little chilly. Out on my balcony, next to the wall so that our apartment can block strong winds and western sun, was a location that met these needs and made it easy to monitor the cocoons daily.

When choosing a location, be aware of neighboring hazards. Another reason I chose the balcony, instead of down in my garden, is that several of my neighbors let their cats roam the complex courtyard. A fluttering moth would be an all too tempting target for a cat, so the house needed to go somewhere the cats do not have access. Consider nearby pets, foot traffic, playing children, etc. and opt for somewhere least likely to be disturbed.

Position the moth house at an angle so that the tarp sides shield the inhabitants from direct, prolonged daylight. My tarp faces the east, to block strong morning sun, and the building blocks the western afternoon light. The nocturnal moths will prefer shade, though having a sense of daytime is important for their internal clocks.

WEIGHTS

Keep in mind that your anchor tabs can slide side to side on the base PVC to accommodate your location. You could center them both, or, for even more stable footing, slide one all the way left and one all the way right. Weighing down the opposite corners will give you the most firm grounding if the breeze kicks up.

Using heavy potted plants as your weight provides an attractive solution. Bricks or cinder blocks will serve you well too, if that's what you have handy. For my rear weight I used my iron plant stand, which hasn't budged even in the craziest Santa Ana winds.

My eBay order of 3 cocoons arrived very carefully packaged and cushioned with cotton. To provide the hatching moths with ample room to emerge, climb, and dry, I attached the cocoons to the fiberglass screen.

Note that this outer, semi-fuzzy cocoon you see is actually an extra, outer layer made of dead leaves and silk. The true pupae (the developing insect) is smaller unit INSIDE this leaf/ silk shell. If you pick up the cocoon gently (handle as seldom as possible to avoid any mishaps), you may be able to feel the pupae roll around in there. Sometimes the insect even wakes up a little and you can feel a twitching. This is normal and nothing to worry about.

To Hang Cocoons:

Hold the cocoon vertically, from one of the tapered ends. The pupae inside will shift to the bottom of the pod.

Carefully insert a safety pin into the very tip top of the cocoon. Since the pupae is now sitting at the bottom, you will not hurt it.

Entering the moth house though one of your door flaps, carefully run the safety pin through the adjacent screen wall.

Close the pin to secure.

Repeat with any remaining cocoons. If you have multiple cocoons, stagger the height at which they are pinned so that 2 moths emerging at the same time won't be bumping into each other.

* It is recommended to lightly mist the cocoons every few days. While the supplier I brought from did not explain why, I suspect it keeps the cocoon materials moist and thus easier to break through when the right time comes, in addition to mimicking the moisture a cocoon in the wild would encounter through the seasons.

You have several weeks before the cocoons will hatch, which gives you some time to browse the neighborhood for suitable moth aviary decor.

Keep it Minimalist. While your first inclination may be to provide a lush habitat, there are 2 good reasons to keep things simple:

--You don't want to ruin all that nice clear, flight space by clogging it up with branches. While these moths are large, their wings are still delicate and prone to chipping and tearing if they are working in a tight space.

--Should a mating pair produce eggs, you want to be able to find them easily so they can be moved to a nursery container. Having a ton of foliage to examine will be a time sucker.

Providing just a few bare branches gives the moths a place to rest without cluttering up the space. Thinner, flexible branches like those from a climbing plant work well because you can maneuver them into the enclosure without risk of tearing the screen. Choose branches that are no more than half the height of your aviary. Keeping the "furniture" low reduces the risk of wing damage. I stuck my branches in a small succulent pot to keep the bases stable.

Some blogs I read suggested hanging a small brown paper sack on one of the branches. A female moth will opt to deposit her eggs on the paper surface, since it is the most leaf like item in the enclosure. This makes for easy identification and removal.

My first female hatched on St. Patrick's Day morning, a bit ahead of schedule. She has a chip out of one wing and I am unsure whether that was damaged when emerging or if it was a developmental defect. After several hours pumping her wings, she was mobile. While I do not recommend "playing with" your moths, they are very docile and their chubbiness makes them easy to handle. I snapped a photo of her on my hand when I helped her back up from a tumble.

If you have multiple cocoons, you may find yourself confused as to which one your moth came from. All of them looked perfectly undisturbed, even though I knew one now had to be empty. What I learned via some YouTube research is that the moth emerges from a pretty small hole on one end of the cocoon. This hole is called the "vent". When spinning the silk, the caterpillar makes this end a lot looser so it can be squeezed through. The cocoon facade doesn't split open as obviously as the chrysalis of a butterfly, which is usually left obviously torn.

After carefully handling each cocoon and guessing by weight which was vacant, I used small nail scissors to cut open the silk. Since I was operating on my best guess, but wasn't certain, I worked slowly and carefully. Fortunately, I was correct. While the outer silk seemed very intact to the untrained eye, the pupae casing was definitely split and empty. The dark shell you see inside is the actual pupae casing in which the moth developed.

*Again, I do not recommend excess handling of the cocoons or moths, but if for some reason you are concerned the pupae may not be viable (maybe it's getting way late in the spring and you still haven't had a hatch), you can trim open that outer silk covering and take a look. As long as you do not pierce or crush the actual pupae, the moth will be fine. After checking the pupae, you can lay the silk back into place and re-hang. Being exposed to the open air will not hurt the pupae.

ADULT MOTH CARE The adult moth's only purpose is to mate and create the next generation. You do not need to provide a food source because they do not eat. In fact, they don't even possess a mouth or digestive system. They are born with a finite amount of energy reserves meant to be used up. For me as an avid pet owner, initially this felt very odd and somewhat cruel, but the fact of the matter is that this is how they are built and they do not feel hunger or pain for lack of food. All an adult moth requires is a safe space with good footing (your screen and branches) and access to a mate so it can fulfill its evolutionary drive. Cecropia moth adults are reported to live anywhere from 4 -14 days. The cycle then begins anew with any eggs they have left you.

Monitor your moths and cocoons daily. You shouldn't have to get in and out of the aviary much. The only times worth putting your hands in are to remove eggs or to correct fallen decor that might cause a problem.

After only one day out, the female began laying eggs like crazy. She deposited them on the brown paper sack, as expected, but also all over the tarp walls and one of the other cocoons. Since the male isn't out yet and our local Cecropia population is scarce (making it unlikely that she was visited by a wild suitor), my guess is that these eggs are not viable. Still, it was very cool to see them and study which surfaces a moth mom deems good for eggs.

I am now at a point where the other two cocoons should hatch any day. My hope is that their life spans will overlap with this first moth so i have a group. Based on the size and formations on the pupae, I believe I have a male and female. I will keep this Ible up to date as they emerge, and then hope to document the mating and caterpillar raising process. Stay tuned!