Raising Rearing Giant Silkworm Saturniidae Moth Caterpillars Hyalophora Cecropia

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PLEASE, PLEASE, PLEASE -- READ THIS PAGE!!! Come back to it often. Compare. Make certain you are following instructions to the letter. If your caterpillars are dying, they are probably dehydrating due to improper set-up of their habitat. This is what you need to do and how to do it!!!! Do not mix and match rearing methods. Method 1 is super simple yet effective. Method 2 is more natural.

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Rearing supplements (other pages):

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BASICS: Keep your ova indoors (exception: sleeve rearing*) and out of direct sunlight. Maintain proper humidification by keeping your containers sealed. Do not mix plant matter with ova. There must be no water or condensation inside ova containers.

*If sleeve rearing, do NOT put livestock outdoors until after the local wild flight, as cold nights will kill ova and caterpillars.

This page was initially developed for raising cecropias, but is relevant for all giant silkworm moths.

Food Plants per Species

  • Cecropia (univoltine) food plants:
    • wild black cherry
    • birch
    • willow
    • apple
    • elm
    • lilac
    • plum
    • Mexican plum
    • white oak
    • alder
    • beech
    • tamarack
    • ash
    • dogwood
    • box elder
    • poplar
    • cherry
    • gooseberry
    • maple (but not red)
  • Luna (multivoltine) food plants:
    • sweetgum
    • paper birch
    • oak
    • black walnut
    • walnut
    • persimmon
  • Polyphemus (bivoltine) food plants:
    • paper birch
    • oak
    • maple
    • willow
    • hickory
    • beech
    • honey locust
    • walnut
  • Cynthia (bivoltine) food plants:
    • Ailanthus (Chinese tree of heaven)
    • wild black cherry
    • paper birch
    • maple
    • willow
    • sassafras
    • sweetgum
    • pin cherry
  • Promethea (multivoltine) food plants:
    • birch
    • sweetgum
    • maple
    • sassafras
    • spicebush
  • Io (multivoltine) food plants:
    • black alder
    • red maple
    • sassafras
    • sweetgum
  • Regalis/Hickory Horned Devil (univoltine) food plants:
    • various hickories
    • black walnut
    • English walnut
    • maple
    • butternut
    • cotton
    • persimmon
    • filbert
    • ash
    • bush honeysuckle
    • buttonbush
    • privet

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Rearing Method 1

Don't use with sassafras

Click to enlarge

Nursery container can hold up to one dozen first and second instar caterpillars

Nursery Container

Items needed:

  • Clear, round plastic deli containers with snap-on lids
  • Floral water tubes
  • Ice cream buckets or alternative large, lidded containers (for later instars)
  • An available food plant

1. When you receive your shipment of ova, remove them from packaging immediately, put them in a lidded deli container, and seal it. Of course, you can peek inside occasionally and/or take photos. Otherwise, keep it sealed so eggs don't dry out. Do not put any leaves in it, or anything other than the ova. If ova are attached to any paper, that's okay. The purpose of this arrangement is two-fold: to minimize air flow so eggs don't dry out and also to prevent excessive moisture from causing mold to grow. Both mold and dryness are deadly to eggs and caterpillars.

Intermediate container for larger caterpillars

Intermediate Container

2. Never keep ova or caterpillars in direct sunlight.

3. Ova generally hatch in 10 to 14 days, depending on the weather (warm weather speeds the process, while cold weather slows it down). Most hatching will suddenly occur within about 24 hours, first on one day, then another. Eggs usually hatch in the morning (this varies by species). Separate hatchlings from eggs by moving one or the other to a different container. Groups of six caterpillars per container are good, but more at this point probably won't hurt. If moving the hatchlings, do so by very gently pushing the edge of a leaf against them, one at a time, to encourage them to climb aboard. You can also use a fine brush or some other item that will get the job done without harming the caterpillars.

4. The day's hatching will probably be completed within a few hours, so move them promptly and provide them with food.

5. It's essential that you provide caterpillars with hydrated food! Plan ahead, so you are prepared when the hatchlings appear. Get a couple floral tubes from your nearest greenhouse, as plucked leaves wilt quickly, and caterpillars won't eat wilted leaves. Hatchlings will not start feeding on wilted leaves.

Ice cream bucket for the really big guys

Container for large pillars



6. Hydrate/water your leaves. Put a piece of wet paper toweling in a floral tube, along with a little water (use discretion so the leaves don't dry out, but neither is the tube waterlogged and drippy), cap the tube, and push the stems of one or two leaves into the hole against the paper toweling. Place one of these in each deli container of caterpillars. Make certain no water is leaking out and no water droplets (or worse) are in the deli container, as water and/or condensation are deadly. Set the tube at a slant, hole end up. Seal the deli container. Again, you can open periodically to observe or take photos. Otherwise, keep it sealed so the caterpillars don't dry out.

7. Limit the number of leaves provided for hatchlings. A brood of twelve only needs one or two leaves. If you're unsure of what they'll eat, put one each of a couple of leaf species in the floral tube, and observe what they choose.

8. It's not unusual for hatchlings to spend as many as twelve hours cruising around before settling on a leaf to eat, especially if it's not a favorite food. Be patient, but after twelve hours it's time to try some other food options, quickly, or read through this page again to make certain you're doing things correctly. In many cases, if caterpillars have not started feeding on a known food plant within twelve hours, it's because they are desiccating. Your container needs to be sealed; I can't emphasize that enough. Air movement dries them out. Remember: they are not in their natural environment.

9. Carefully maintain hydration of leaves. Small caterpillars don't eat a lot (but they do eat a lot for their size, and often), so the leaves must be kept fresh and hydrated/watered. Change leaves every two days, or before that if they're eaten away. Always keep them watered.

10. Once started on a particular food plant, the caterpillars will not change, so make certain you have an ample supply available of the plant you've chosen. Caterpillars might be willing to change to their natural food plant, but that's the limit (and I only know that wild black cherry is cecropias' natural food). Some people have experimented successfully with getting caterpillars to switch following a molt.

11. Caterpillars poop. The poop is called frass. It is dry and uniform in shape. You will notice it collecting in their containers. To prevent disease, dump it once each day or two. Make certain all the caterpillars are on the leaves, lift out the tube of leaves and set on the lid, then dump the frass outside.

12. Even hatchlings start producing frass as soon as they start eating, and they should start eating within about twelve hours of hatching. If there's no frass collecting in the container within roughly twelve hours, something is wrong.

13. After a few days of eating, the caterpillars will become very still. Do not disturb them, as they are poised to molt their skin. This takes about a day. When they become active again, they will resume eating. They will also look different, as they change appearance somewhat with each molt. Continue to maintain their leaf supply when they are active again.

14. Caterpillar skin is not capable of expansion-growth. Rather, a caterpillar grows a new, larger skin under the old skin, molts the old skin, and grows into the new skin. When growth reaches the skin's limit, the caterpillar molts again. This happens four times. Each skin is called an instar, so caterpillars have five instar stages, during which they eat. When the fifth instar stage is completed, the caterpillar makes a cocoon, pupates, and enters a dormant state for a few weeks or until the following spring. The adult moth emerges from the cocoon at its appropriate time.

15. If the caterpillars seem crowded in their containers, set up more containers and shift some caterpillars. Otherwise, continue caring for them as you've been doing. Notice that the frass is bigger with each new instar. Also, they'll be eating more. Make certain they have ample food.

16. When the caterpillars are into their third instar, it will be time to rearrange/change their habitat. This is where I use ice cream buckets, for a number of reason.

17. You can recycle your deli containers or use something different. What you need is a lidded container that is not very high (I used a sour cream container). Punch two or three holes in the lid with a phillips screwdriver, fill the container with water, and put the lid on. Take cuttings from your food plant that are not real long but have lots of healthy leaves, and push the stems through the holes and into the water. Set in ice cream bucket and shove all the leaves inside. Move a floral tube of leaves/caterpillars to the ice cream bucket and leave it. The happy caterpillars will quickly abandon the old leaves and crawl into the foliage.

18. (Third instar cecropia caterpillars are brightly colored and very pretty. I think number three is their handsomest instar.)

19. I did punch a single hole in the lid of my ice cream bucket, dead center. Don't know whether it was actually needed or not (it's not). It didn't hurt. I kept the bucket sealed at night, if I was away, or if the A/C was running. Caterpillars are less prone to drying out at this point, but A/C, or any artificial climate control, can suck the life right out of them.

20. Frass dumping is easy with the ice cream bucket. Just set the plant container on the bucket lid and then dump the bucket outside. If you wash it, make certain it's thoroughly dry inside, always to prevent mold growth.

21. The reason why I set the plants on the lids when dumping is to try to prevent new frass from dropping elsewhere. Caterpillars produce loads of the stuff. Keep that in mind.

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Rearing Method 2

Provided by Bryan Yenish

Click images for larger view.

Twig hanging from inner lid Wet paper toweling on top of lid
Large container and netting Food plant provision in large container

Do NOT mix and match rearing methods. If using Bryan's method that includes misting and damp paper toweling, don't seal the containers. The extra hydration compensates for open air. But do keep in mind that Bryan's rearing room is not air conditioned and the windows are kept closed, which still limits air movement. We never recommend directly exposing caterpillars to any artificial climate control.

1. For instars one and two, I use Rubbermaid containers with small airholes punched through the tops and a couple larger holes for inserting cut stems or leaf ends through. The caterpillars hang freely that way, so their frass falls straight down and does not stick to leaves.

2. In the second photo, I wrap the stem or leaf in a piece of dry paper towel, then tape it to the container lid. I spray the paper towel using a spray bottle; this keeps the leaves fresh for five days, as long as I keep spraying the paper towel and cutting the stem or leaf end every couple days.

3. For the remaining instars, I use 40 to 60 quart storage tubs with the lids cut out, except for the outer frame, as I use thin bridal netting for a screen at the top. The lids snap down on the netting to prevent the caterpillars from escaping.

4. I use mini water bottles to hydrate larger cut stems; I drill holes through the caps on the water bottles. I also use double sided velcro tabs for the bottom of the water bottles, so they won't tip over. I cut the stem bottoms every day, about a quarter inch; you would be surprised how much water the stems suck up every day. Food can be kept fresh for 5 days this way, and I always mist leaves with Poland Spring water [the best], and place a wet paper towel on the tub floor to keep humidity level up. This compensates for the drying effect of moving air, which can be deadly to caterpillars, as it sucks the moisture out of them (but always be watchful that condensation isn't forming on the insides of the containers). In the wild, the trees they live in are constantly losing moisture through their leaves, and this escaping moisture creates a humid environment within the tree canopy, which helps keep caterpillars hydrated along with the food they eat. Also, some species are typically found near lakes, streams, and marshes, where evaporation adds still more humidity to the air. This is why they don't dry out in their natural environment.

5. The room Bryan uses for rearing caterpillars is not air conditioned and the windows are closed; thus, there is no significant air movement going on. Add to that the fact that he mists the containers and keeps wet paper toweling on the bottom -- this is why he is able to use containers that are not air tight.

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Beyond Rearing

1. If ever you notice a caterpillar looking discolored or producing loose frass, remove it to isolation as it could be diseased and you don't want disease to spread. I've never had this happen, but when it does happen, it is fast spreading and devastating.

2. The molting process remains the same except time between molts might become longer. Frass gets bigger with each instar. If caterpillars seem crowded, create more habitats.

3. Fifth instar caterpillars become huge and eat voraciously. Mentally prepare yourself for this. Make certain they have adequate food. This instar lasts roughly two weeks.

4. Prior to pupation, caterpillars stop eating forever and empty their guts via a huge, loose mess. Watch for this, as it is both normal and a warning to you. Once the critter unloads and recovers from its bellyache, it's going to feel pounds lighter and will take off like a streak in search of a perfect place to cocoon. Keep the lid on your bucket until all the critters within are making cocoons. Once that is started, they won't go anywhere anymore.

5. It takes a couple days of nonstop work to complete a cocoon. Once completed, let it dry and stiffen thoroughly before removing it. It can then be peeled off the bucket, leaves can be pulled off, some twigs can be pulled off. If anything is stubborn, just trim the stuff away instead -- leaves and twigs. Don't cut the cocoon.

6. If your home isn't excessively dry, the cocoons can sit around. Putting them in a sealed container won't hurt. I refrigerate mine when all hope of Indian summer is past, and hard freezes are commonplace. Seal them in freezer bags; several to a bag. Do not put in freezer. I keep mine in a crisper, but it's not necessary if sealed in a bag. I do it in case the fridge temperature drops to freezing. I also keep them in a cardboard box, as cardboard is a good insulator in case the fridge temp. drops too low.

7. I slit my cocoons open, to inventory genders and because pupae are interesting. Because the cocoons are open, I take extra precautions to protect them from the refrigerator environment, as explained in previous paragraph. They need to be in cold storage, but the open cocoons can't fully protect them from extremes.

8. Find out what the eclosure time is in your region (approximate is fine) and remove cocoons from refrigeration about four weeks before. Putting them outside helps synchronize them to the wild population, but keep them protected from predators (rodents mostly), direct sunlight, pooling rain. Do not keep in a garage. Otherwise, just keep them in the house and whatever happens, happens.

9. Eclosing moths need to climb up onto something they can hang from to inflate and dry their wings. They will spray, so have something absorbent below them. Spread it around because we're talking about spraying under pressure. It squirts around.

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Wasting Failure

Wasting failure looks like prepupation without a cocoon, photo by G. Larson of California, used with permission

1. Some of us have been experiencing a fifth instar cecropia wasting disease. Bryan and I have no definitive answers, as we've not experienced this, but we are concerned. Because of this, we have conferenced between the two of us, and Bryan has consulted with a friend who is a very avid moth raiser. He's experienced the problem.

2. The friend's experience happened with indoor reared cecropias feeding on red maple, two summers in a row. Bryan suggested he try rearing outdoors on red maple, under-crowded, overfed. He did, and his cecropias thrived and cocooned normally.

3. So, Bryan pondered as to why. And he and I pondered together. We have no definitive conclusions, but we are sharing our thoughts and ideas.

Wasting failure, photo by C. Rind of New Hampshire, used with permission
Wasting failure, photo by C. Rind of New Hampshire, used with permission

4. Cecropia's natural food is wild black cherry, a fruit tree. Bryan thinks cecropias do best on fruit trees. However, I always raise on paper birch, and my bugs thrive. I think, though, that Bryan has a point. There is something the fruit trees have, and maybe the birch (multitudes of bugs love birch), that other trees lack. Under ideal conditions, cecropias can live on other trees, but not under less than ideal. Indoor rearing is less than ideal.

5. So, what are ideal conditions?

6. Cecropias are native to the eastern North American continent, including southern Canada, but not in Mexico or the Florida peninsula, the latter probably being too tropical. East of the Rockies, summers tend to be humid with ample rainfall. We get a lot of gulf moisture circulating around. Dew points probably average in the 60s, sometimes climbing into the 70s and 80s. The bugs thrive in this sticky warmth.

7. Cecropias live in tree canopies, on the undersides of leaves, protected from direct sunlight. Tree leaves give off loads of water vapor, and much of that moisture is held within the canopy. When cecropias reach fourth and fifth instar, they no longer live on the leaves but on the twigs. They go where the foliage is dense, and they are hidden from predators. This dense foliage holds in moisture. This is their comfort zone.

8. I've observed that when, at third instar, I move my caterpillars to larger (but not overly large) containers and start feeding leafy twigs instead of leaves, I don't have to coax the pillars to move onto the leafy twigs. They gravitate there very quickly and disappear into the leaves. I tend to use containers that are just large enough to avoid overcrowding, but close enough so pillars are never far from their food source. I stuff a lot of leafy twigs into the container, in part because they eat a lot, but also because they like it that way. Pillars don't just eat leaves; they live in and on leaves. The leafy environment is their habitat.

9. Placing stems of leaves or twigs in water is extremely important. Picked plants lose moisture quickly unless they are placed in vases of water.

10. The close containers, stuffed full of well hydrated plants, hold in the moisture that the leaves are constantly giving off, thus mimicking the moist natural environment of wild caterpillars.

11. Indirect but bright sunlight is important. Sunlight increases the warmth of the insect environment. Warmth is very important. If rearing indoors, using artificial climate control is not a good idea. Besides its drying effect, air conditioning neutralizes the summer heat and humidity that caterpillars require (but don't ever compensate by keeping them in a garage because garages get dry and overly hot).

12. Like with rain and dew, caterpillars can use some extra moisture. I admit I don't mist, but I do recommend misting the artificial environment using a spray bottle and water from a safe source, be it rain or something not chlorinated. Do not over-mist; mold growth can be deadly.

13. Whenever there is any sign of disease, isolate sick pillars, and clean containers thoroughly with diluted bleach. In the case of this wasting disease, I'm thinking it's a nutritional or environmental deficiency, a vague sort of lack that occurs with indoor container rearing, rather than a pathogen; however, never take a chance.

14. Additional information: I ran this whole matter by a professional lepidoptera keeper, who said there is a bacterial disease that produces results like in the photos. He said it usually happens when feeding paper birch late in the season. However, of the three parties I know of who reported this disease to me, two were feeding red maple and one was feeding cherry. The professional emphasized good hygiene. He said he uses diluted bleach and also a virucide, and washes everything, including what he touches.

15. The professional also stated that red maple is a poor food choice for cecropias. Nutritionally, it doesn't do the job.

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Diapause Care

1. ALWAYS keep your insects from drying out. Seal them in a plastic container or freezer bag. Open periodically to freshen the air inside, but don't worry that the bugs will suffocate. Yes, they breathe, but they are not heavy breathers; there is sufficient air in a sealed enclosure. When the weather turns wintry, refrigerate (literally; don't put in freezer!) them for the winter. Do not just put in a garage. If you must have a specific date, then we suggest around November 1st.

Do not refrigerate prematurely out of concern for a possible early eclosure. Univoltine species like cecropia are not going to eclose before winter. The earliest eclosures will happen around the vernal equinox and much later in northern climates. As for multivoltine species, their time table is predetermined; if a moth is destined to eclose during the same year as its caterpillar stage, refrigerating it won't change that. You'll only kill it. Therefore, don't refrigerate till around Nov. 1.

2. To determine your area's wild flight, for breeding purposes, do a web search for your state. If you are west of the Rockies, then don't bother. There are very few, if any, of these moths west of the Rockies, except in one or two very isolated areas where there is sufficient moisture and trees to support them. Otherwise, just watch your local deciduous trees for leafing. Watch for the tiny leaves to appear.

3. Remove your bugs from winter storage around 3.5 to 4 weeks before your peak wild flight (or when your trees start leafing). Never put bugs in direct sunlight. Protect them from excessive dryness due to running furnace or air conditioning. NEVER keep in garage. Provide them with ample space and something to climb up on so they can hang to expand and dry their wings.

Page Index

Bryan's Spring Emergence/Eclosure Set-up

The emergence set-up is for in home use only. Don't put this in a garage or outdoors. If you live in a very dry climate or are running artificial climate control in your home most of the time, then don't cut the center out of the lid. There is more than ample O2 in a tub for insects to breathe. Click images to enlarge them.

Two sizes of eclosing tubs

Two different sizes of emergence/eclosure tubs, placed one inside the other for efficiency only. The large tub is a 40 quart size storage container with lid, and the other is a 4 quart size. The large tub is good for 10 to 20 cocoons; use the small size for fewer than ten. In each case, the lid's center section has been cut away.

A tub is prepared by lining it with paper toweling before adding cocoons.

Line the entire inside of the emergence tub with paper toweling. There is no easy way to do this; use tape. Place cocoons on the bottom of the tub. Shown on the bottom, left to right, are cecropia, polyphemus, and luna. Cynthia and promethea need to be hung on the side of the tub, as shown. In the wild, they hang like Christmas tree ornaments.

The paper toweling is dual purpose: It's an easy surface for moths to crawl and climb on, essential for wing expansion, and it absorbs all the fluids that new moths release. Also, the tub can be placed in direct sunlight because of the paper toweling. Never leave unshaded moths, at any stage, in direct sunlight.

Drape mesh over the tub's opening and then snap the lid on.

Last, place some screening over the tub opening, then secure the cover over it. This mesh material is available at craft stores by the foot. Place tub by a window so pupae can sense the longer spring daylight hours. They will eclose in perfect condition. Moths tend to eclose mid morning through early afternoon.

I (Peg) have been using cages for eclosure, but I liked this idea of Bryan's, so went out and bought a container. It's a small container because I raise only small numbers of moths, for pleasure and to photograph and journal for the website. (My passions are observation, documentation, and experimentation.) I actually would have been pleased to find a container about twice the size of this one but having the same proportions. Didn't happen.

Obviously, I can't cut the lid of this thing apart, but I see no need to. Do NOT, however, keep a sealed container in direct sunlight. It would cook inside. In this northern continental climate that I live in, our springs can get cold. When that happens, the furnace gets turned on, and artificial climate control is never good for moths. It sucks the moisture out of their bodies and they die. There is ample oxygen in any sealed container to sustain little moths. And, if I think the bugs need some fresh air, I can always take the cover off and fasten cheesecloth to the top using a big rubber band.

Base is lined with paper toweling; lid has cheesecloth taped to its underside.I'll prop the cocoons against the back wall of the tub so the moths climb all the way to the top.Cheesecloth is held in place with duck tape. I used clear tape for the paper toweling.

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Hand Pairing - A Last Resort

Hold the moths together, touching each other so the bottoms of their bodies are aligned, head to head, tail to tail. Watch for the male to open his claspers, which they tend to do when they contact a female. At same time, watch for her to extend her ovipositor. You must get his open claspers around her ovipositor, and when he closes them on it, they are joined. Carefully set them down and leave them alone. Do this during the night, as that's when moths are active for mating. Try to find out at what time of night the species typically mates.

Polyphemus ovipositor fully extended.Polyphemus ovipositor partially extended.

The female moth ovipositor serves several purposes. It contains a scent gland that attracts male moths. A female must extend the ovipositor to "call" males to her. A calling moth is easily recognized.

The ovipositor is also the mating organ. For mating to occur, it must be extended. The male moth connects itself to the female by clasping onto the ovipositor with his clasping organs, which are little plates that open and close. A male opens them only when he is in close proximity to a calling female. Physical contact is important. NEVER try separating a pair of moths that are connected. If the male doesn't release the female, the ovipositor will be torn out of her, and she is doomed.

Lastly, the female moth deposits her eggs with her ovipositor. It is a movable, retractable organ, and she extends it, places an egg and some glue, and then retracts, shifts to a new position, and repeats, over and over. Moths mostly lay their eggs in the exact same position and direction, over and over. The little pillars tend to all escape in the same direction as the result. Rarely does one egg's position block the escape route of another egg's occupant. Instead, the pillars all head straight out in a little, semi-organized group.

Page Index

See my cecropia page for more information and ideas.

Please note: If you are inquiring about moth rearing but are a different vendor's customer, please read the information on this web site, but contact your own vendor instead. I will gladly answer customer questions on this topic, but non customers are making inconsiderate demands of my time, and I am too busy for this. My information is already available on this site. Please make use of it.

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