HOW TO REAR SATURNIID MOTHS (giant silk moths)

Beginner-level info for rearing Polyphemus, Luna, Cynthia,
Cecropia, Promethea, Io, Regal, and Imperial moths. 
(The first 3 species are the easiest to rear.)

by Liz Day 
(Copyright 1998-2009; ask for permission to reproduce.)
Last updated March 16, 2010.

NB:  If you're in the northern half of the US, and your moths are emerging
now, it's too early!   If your cocoon overwintered some place warmer than
outdoors, this can happen.   They should emerge after the trees have 
leafed out. 
The moth will not find a mate outdoors at this time of year.  It can be kept
for a few days to observe, and then frozen to pin it as a specimen, or
released outside and a bird will probably eat it.  Sorry for the depressing
news.... they are cued carefully to temperature and light conditions.

Full grown regal moth caterpillar (about 5" long).
Photo by Ron Foster. 

Large (4th instar) cecropia moth caterpillar. First and second instars of cecropia. Note how different the young larvae look from the later stage. Photos by Betty Cessna.
Female imperial moth laying eggs on a wall in Florida (not normal behavior, but a good closeup). Photo by Abhijit Wakchaure. GOOD BOOKS AND GUIDES: For more detail on saturniid moths (a large book, not a field guide): "Wild Silk Moths of North America" (1996) by Tuskes, Tuttle, and Collins. For moths in general: "Field Guide to Moths of Eastern North America" by Charles Covell. For caterpillars (both moths and butterflies): "Caterpillars of Eastern North America" (2005) by David Wagner. There are very few good guides to moths or larvae; these are among the best. A link to a mailing list about raising silkmoths: click here COMING SOON...:-) TABLE OF CONTENTS
  • Introduction
  • Obtaining Eggs (includes info on blacklighting)
  • Note to Teachers
  • Eggs
  • What to Feed (includes food tree ID photos)
  • Young Larvae
  • Larger Larvae (includes info on predators and disease)
  • Pupae and Cocoons (includes info on diapause and overwintering)
  • Adult Moths (includes info on telling male from female and on mating)
  • Further Reading
  • Acknowledgments
  • Introduction Giant silk moths and their caterpillars are spectacular and exotic-looking. Go to the library and check out the paintings in "Wings of Paradise" by John Cody. (Or search the web for examples from his book, e.g. this site.)
  • Obtaining eggs Get eggs from wild female moths. Any female flying around can be assumed to have fertile eggs. Saturniid moths live in wooded areas away from large cities. They will come to a strong light set up to shine on a bedsheet. You will only get whatever species are flying at that season of the year and time of night. Usually most of the moths are male, but a few are female. See later in this article for how to tell the sexes apart and how to enclose a pregnant female. Another way to obtain eggs is to find cocoons in winter attached to twigs. If the cocoon hatches into a female, she can call in a male (see later on). Some people sell or trade eggs and cocoons by mail. In the US, interstate shipment requires a permit from the USDA. (The USDA may change these rules, but has not done so yet.) A source of eggs and cocoons (Bill Oehlke's web site). For other countries, ask the supplier what rules apply. If you buy or trade livestock, please follow basic conservation ethics. Do not import a species that is not native to your area. Don't release animals from distant states into the wild, as they could introduce saturniid parasites or diseases.
  • NOTE TO TEACHERS If you are raising moths for your classroom, I recommend luna, polyphemus, promethea, cecropia, or cynthia. Avoid regal and imperial, because the pupae are hard to keep alive, and avoid io, because they sting. The moth life cycle will not be completed in one semester. In Indiana, the moth emerges from the cocoon in spring (say in May) (these times are all VERY approximate). It mates, lays eggs, and dies (this takes several days). Eggs hatch in 1-2 weeks; caterpillars grow for 3-6 weeks before spinning cocoons in June or July; the cocoons hatch about a month later (except cecropia, which has only one brood per year); you get a second generation of caterpillars in late summer; these spin cocoons around September, and remain dormant until the following spring. (Or they SHOULD - sometimes they get confused and hatch in October; see the section on hibernation.) Thus, if you obtain eggs or larvae in late summer, the students can see them grow to full size and spin cocoons. Then, if you keep the cocoons over winter (or obtain cocoons during winter), you can bring them indoors in spring a couple of weeks early, which will often persuade the moths to emerge before school is out. Note also that the same principles described here for understanding the needs of saturniid moths can be applied to rearing many other kinds of moths and butterflies. Things to see: "Blacklighting" for moths is a memorable experience. If the habitat is good, scores or hundreds of moths and other insects gather on the sheet where you can pick them right up and look at them. click for a photo (this is unusually good, not to be expected everywhere) There are so many different kinds it will keep you up all night. Most people do not own a blacklight and generator, but you can go out with someone who does. You can also attract moths using the battery-powered camping lights that use fluorescent bulbs. Set two of them (ideally, one regular and one black-light bulb) so they shine on a bedsheet. If you live near decent habitat, you can also attract moths right into your house while you do other things, by turning on a very bright light and opening the window. When you're finished looking at the moths, turn off the light and leave the window open; many of them will leave during the remainder of the night. (The rest you'll have to catch and put out.) This is a relaxing way to avoid work, both the work of hauling blacklight equipment out to the sticks, and the other work you were supposed to have been doing at home. :-)
  • Eggs Keep the eggs in any small container with the lid closed, so the larvae don't escape when they hatch. If the air is very dry, mist the eggs occasionally. Never put leaves in with the eggs - the leaves give off CO2 and the eggs may suffocate. For the same reason, the container should not be totally airtight. If the eggs were laid on leaves, let the leaves dry up and die before enclosing them. Eggs hatch in about 10-15 days. Things to see: Often the newly-hatched larva eats its egg shell for protein.
  • What to Feed If you already have a caterpillar, feed it whatever it has been eating, as they are reluctant to switch foodplants once they start. If you have freshly hatched larvae from eggs, you can choose what to feed. Field guides and other sources list the food plants for various species. Pick a tree that you can visit often and get plenty of leaves from. All the moth species listed above will eat sweetgum (Liquidambar). I recommend this tree as the leaves stay fresh well when cut. It is common in forests and planted along streets in many parts of the East and Midwest. FOR ID PURPOSES: Picture of sweetgum leaves.
    Picture of sweetgum gumball.
    Pictures of sweetgum branch with fruit.
    Note the star-shaped leaves and spiky gumballs. Sweetgum is aromatic - it smells like pine resin.
  • Young larvae The main problems with just-hatched larvae are that they sometimes crawl off their food before they begin to eat, and they can dry up and die quickly. To prevent these problems, as soon as the larvae hatch I move them to a Tupperware-type plastic container. It is easy to pick them up with a soft artist's paintbrush. Put a sheet of damp paper towel on the bottom, lay fresh leaves on it, and close the lid. (Use leaves that are mature, but not old and leathery; do not use young new leaves.) This arrangement makes it easy to keep track of the caterpillars, and keeps them close to their food. The humid air keeps the leaves alive and the larvae from drying out when they are very small. Every 12-24 hours, empty the container and rinse it, replace the paper towel with a new one, knock off any droppings stuck to the leaves or the larvae, and gently shake or blot off excess water. Never pull larvae off the paper towel - instead cut out the little piece they're on. (It's better to use scissors than to try to rip it, as the larvae can be ripped when the part they are sitting on is stretched.) Adjust the amount of water you leave in the towel, so that when you close the lid, the environment inside the container will be humid but not wet. Make sure the larvae themselves are not wet. Excessive dampness promotes disease. I keep larvae in this container until they have molted at least once. You can tell if they've molted because in most species they change color and appearance with each molt, and because the head capsule is much larger at each new stage ("instar"). You may want them to switch to another food plant species partway through their development. Sometimes this can be done, and other times they will refuse to switch. (When larvae keep marching off instead of staying put, it often means they do not prefer the food they're on.) Put them on the new kind of food, replace them if they walk away, and watch closely to be sure they're eating it. (If they're eating, they'll be making droppings.) An ideal time to switch foods is right after a larva has molted, before it gets started on the old food again. At this time it hasn't eaten in a few days and is ravenous. Things to see: In some species, young larvae cluster together on the leaf. This may keep anyone from being isolated on a leaf edge where it could fall off when another larva chews through the leaf closer to the base; or perhaps clustering has some anti-predator effect.
  • Larger larvae Wild saturniid caterpillars live up in trees, where they are surrounded with free-moving, warm, humid, summer air. When it's hot and sticky out, and people are becoming uncomfortable, that's when larvae are just hitting their stride. Avoid air conditioning, which is cold and dry; it will slow their growth. Don't keep larvae closed up inside a container where the air will get excessively damp and stagnant. (When small larvae live in plastic containers, I open and clean the containers every day. I don't keep larger larvae closed up like this.) In the wild, their droppings fall to the ground far away. Thus, don't let them sit in old leaves and frass (droppings). Larvae are susceptible to many fungal and viral diseases. These often are incurable and fatal. Many diseases are transmitted by one larva contacting the droppings of another, by the rearer handling sick larvae, by dripping water/excess dampness, and by mold from damp droppings. If you see a sick caterpillar, get it away from the others. Knock or rinse any droppings off the leaves. Your best strategy for handling a disease outbreak is to immediately isolate the healthy larvae from any that appear at all sick and discard or disinfect anything the sick larvae have touched. Sooner or later, you will probably lose some or all of a brood to disease. Every rearer experiences this, no matter how well they care for their larvae. Luna and polyphemus seem to be the least prone to illness, but no species is immune. Don't beat yourself up if some die. See this link for more on viral diseases: click here (Faloat's butterfly web site) In the wild, saturniid larvae get some amount of sunlight. They apparently need natural light or its equivalent to survive, but no one knows exactly what kind of light or how much. Mine have done well in summer shade. Be careful with direct sun - it's hot! I keep my larvae either outdoors, or indoors by an open window. They live on branches stuck in a bottle of water. If they are outdoors, all this is enclosed in nylon bridal mesh (buy at fabric stores). The mesh keeps most predators out and the caterpillars from walking away. You can also put them out on tree branches inside mesh sleeves. if they are indoors, I set the bottles on the bottom of a large open plastic container so the frass will be easy to dump out. I remove frass every day. I cut the stems twice a day, as otherwise the cut ends seal up and the leaves dry out. Plug the mouth of the water bottle with a wad of paper towel, or the larvae will crawl down into the water and drown. (This behavior seems to demonstrate incomparable stupidity, but probably drowning is not a problem normally encountered by arboreal animals.) THE KEYS TO SUCCESS ARE CLEANLINESS AND FRESH, ABUNDANT FOOD. Don't let them run out of food. They eat (intermittently) 24 hours a day, especially at night. Larvae can drink water, but they obtain most of the water they need from their food. When it is very hot, leaves tend to be dryer (both on the tree and in a vase). You can mist the leaves and the thirsty larvae will move their heads back and forth, vacuuming up the water droplets. However, this technique is only an aid, not a substitute for fresh food. Avoid crowding them - they interfere with each other, which will stunt their growth. Crowding also lets diseases spread. Saturniid caterpillars are not cannibalistic, but might inadvertently bite each other. One caterpillar per leaf is about maximum. When handling, don't pull a caterpillar off a surface - the body will break open before the legs let go. Injured caterpillars die. Instead, cut off the whole leaf the larva is sitting on, and move that to where you want it. When giving them fresh leaves, I just lay the old leaves, stems, larvae and all, onto the fresh ones and let the caterpillars crawl to the new food. When a caterpillar molts, it steps out of its skin. However, first it must attach the outer skin to something so it won't fall off the plant. Before shedding, the larva spins a silk pad, and hooks its feet to it. Sometimes you can see the pad, or you may just see the caterpillar sitting there motionless with its head curled under. They sit this way for about 2 days before shedding. You can see the head capsule falling forward and becoming detached from the face; this is the first stage of molting. Don't disturb them when they're like this. Just cut the whole leaf if you need to move it. Sometimes you will see a caterpillar that has not completely shed - part of the old skin remains wrapped around its middle like a belt. This is probably caused by it having been moved while in the process of shedding. Try to carefully tear or break off the belt of old skin. After shedding, they will be very soft. Avoid handling their bodies then, just hold their leaf. They are vulnerable to attack by ants at this time, especially if they get wet or fall on the ground. I lost many larvae to ants during a rain when they were molting. PREDATORS: Wasps and yellowjackets will attack and kill the caterpillars if they aren't screened out. Many tiny wasp species are parasites of Saturniids, but the mesh will usually keep them out. Birds haven't been a problem for me; I think they don't see the larvae under the mesh. (If they find larvae out in the open, they will eat every last one.) Ants seem to bother larvae under some conditions and not others. Some rearers report that if ants gain access to their larvae, the larvae are all devoured; whereas I have watched predatory ants walk right over larvae every day day for weeks and ignore them. Watch your situation carefully to see what is happening. RACCOONS: Raccoons eat larvae and pupae and are capable of ripping right through mesh coverings and sleeves (or even removing the whole sleeve from a tree). Anything outdoors is subject to their depredation if they find it. You will find a huge mess and not a single larva left. Inside a screen porch is (somewhat) safer. Discourage raccoons by not allowing them to live in your buildings or eat your garbage. Warning: When larvae reach their 5th (last) instar, they are so big that they suddenly start eating a LOT MORE. Overnight, whole branches will be eaten down to the stem, and you'll be running out for more leaves every 24 hours. So don't raise too many larvae, or you'll go crazy. Start with about 50 eggs to allow for mortality, but try to end up with no more than 20 fifth instar larvae. Release the others or give them away. (Click for a cautionary description of larval overload.) When larvae are ready to pupate, they will get what looks like diarrhea - they are emptying their gut to be ready for the next stage. They evacuate their gut in one or two big messes. They also start to wander; in the wild, some species would crawl down off their tree and walk away. At this point you must enclose them so you don't lose them. (Cautionary stories of escaped pillars turning up in funny places omitted). Things to see: A caterpillar's eyes are small and primitive - just little dots on the head capsule near the mouth. They don't see very well. Molting larvae shed their head capsule first. You can see it separating from their face before it falls off. They cannot eat at this time because it's covering their jaws. After the capsule goes, the rest of the skin is shed quickly. Often they eat their shed skins. Large heavy larvae often will prefer not to crawl onto the leaf stalk (petiole), a precarious hold. Instead they will hold onto the main stem with their hind legs, and use their front legs to bend and pull the leaf towards their mouth. They may snip the leaf vein to make it easier to bend. Most insects are constructed like robots, with pieces of hard outer shell operated by muscles inside. But caterpillars are built like water balloons - the water pressure holds them up - and their fleshy legs are operated hydraulically. Watch one walk to see the leg alternately become plump, then collapse. With a magnifying glass, you can also see the little crochet hooks on the bottom of their feet that help them grip. Some saturniid caterpillars are lighter green on the back and darker green underneath. As they rest upside down, the sunlight from above and the shadow cast below make the animal appear to be all the same shade, for camouflage. Hold a larva on a stick in bright light and turn it rightside up and upside down to compare. Don't touch io moth larvae - they sting. With other species, if you pet your larvae often as they get bigger, they will get used to being touched and not mind. Some people say that handling will make the larvae use up too much energy reacting to the touches. This has not been my experience. Prepupae Inside the cocoon, or underground, before it sheds its skin and turns into a pupa, the larva becomes something called a pre- pupa. It shortens a little and can't walk anymore.
  • Pupae and Cocoons COCOON OR PUPA? "Pupa" is the resting stage of the moth or butterfly. In moths the pupa commonly looks like a brownish, torpedo-shaped object. "Cocoon" is the bag of silk that many kinds of moths make to surround the pupa. Some moths don't spin cocoons; instead the pupa is naked. (Butterflies don't spin cocoons either. Instead of being brown and smooth, their pupa is often colorful or strangely shaped, and is called a "chrysalis". It's still a pupa.) Most saturniid caterpillars spin a cocoon in leaves on the tree (e.g. polyphemus, promethea) or on the ground. Sometimes they spin right in the leaves they've been eating; other times they walk off their foodplant and march away. If they do that, put them in a paper bag and fold over the top. Regal and imperial larvae do not make cocoons - they burrow into the ground, and need different treatment (below). THE MYSTERY OF DIAPAUSE (HIBERNATION) Some species have more than one brood a year. Pupae from early summer broods develop right away and hatch into moths in a few weeks. Pupae from late summer broods will not hatch until they have first gone through a cold period (winter). The "decision" of which way to go is made while the animal is still a larva; you can't change it by the way you treat the pupa. If you try to put a pupa that is "programmed" for immediate hatching into the cold, it will just die. When pupae are in warm temperatures, any pupae that don't emerge within 6 weeks are either dead or in diapause. The larva "decides" what to do based on temperature and daylength. Daylength is crucial during the larva's last instars: a long light period (like that in early summer) will cause the pupae to develop and hatch right away, while shorter daylengths make them hibernate. The book _Wild Silk Moths of North America_ by Tuskes, Tuttle, and Collins, says: "A 16-hour photoperiod experienced by 4th-instar polyphemus larvae leads to adult development, and a 12-hour photoperiod produces [hibernation]." But it is much more complicated than this. For instance, what is supposed to happen at a 13.5-hour daylength? I have had had half a batch overwinter and the other half hatch right away; rearers tell me that in some cases, the slightly different environment inside a sleeve vs. in the open air is enough to cause a larva not to diapause. Exactly what cues - an interaction of light, temp, and genetics - are required, I don't know. This is a problem, because a moth that emerges in fall has no hope of posterity. Soon there will be no leaves, and the eggs do not overwinter. In the second half of summer, keep your larvae in the dark at night, so that the pupae will be "programmed" to hibernate and not hatch in October. I suggest putting a box over them. Probably, the closer to outdoor conditions they are kept, the more likely they are to behave correctly for the time of year. CARE OF PUPAE Pupae still breathe; they have spiracles (breathing holes) down their sides. They can't dry out too much or will die. They can't be kept too wet or will mold/rot. Store cocoons outdoors, in the shade, in a rodent-proof cage. Use a container that "breathes" well, not one that is airtight. Cocoons can also be put in an unheated garage or porch, if the container is such that animals can't get them. (In a garage or porch, choose a shaded place, because even in winter, sunlight is hot.) Birds, coons, mice and chipmunks eat pupae! One can make a cage out of hardware cloth (coarse screening found at hardware stores). Such a cage is also useful for containing the moth when it hatches. Do NOT put cocoons in a frost-free refrigerator (except in containers as described below); they'll dehydrate and die. The cocoon helps protect the pupa from drying out (this is why above-ground pupae have cocoons, while below-ground pupae are naked), but it still allows some water vapor to leave, so it cannot protect them completely from the perpetual dryness found in a frij. Luna moths make thin cocoons which are normally covered in leaf litter in the wild. Put some oak leaves, which don't get wet easily, around them to protect them from the weather. Give imperials & regals about 6" of moist peat moss to burrow into, where they will pupate. Peat moss, which is fairly germ- free, seems better to me than soil, which is not very clean. Avoid vermiculite and other materials that are too loose/coarse to hold their shape. If the little cave that the larvae has dug collapses on it, the animal can get deformed when it molts into a pupa. Even if there is nowhere to dig into, the larva will eventually pupate anyway. Thus, you can also just put the larvae in a container with damp paper towels and let them pupate in "the open". Make sure there is humidity. This is a good way to observe the molting, which is strange to see. After they dig in, you should wait at least two weeks before disturbing them, since they may still be soft under the ground. The caterpillar molts into an egg-shaped pupa that first is greenish, then turns dark brown and hardens. Their winter care is something of a pain. My friend had nearly all of his rot over winter for several years until he discovered how to keep them. He stores imperial and regal pupae in the frij, in a special Tupperware arrangement. (If pupae sit in the open in a frost- free frij they will dehydrate and die.) Get a piece of 100% linen (avail at bridal stores). Linen will not get wet in damp air. Put a small amount of water in the bottom of the Tupperware container. Put the pupae on the piece of linen, lay the linen over the open top of the plastic container like a hammock, and close the lid, trapping the edge of the linen in the lid to keep it from falling down. The pupae are now suspended in mid-air inside the container. illustration The linen does not get wet, but the air is kept humid. I open the container every two weeks, check the water level, and blot up any condensation on the lid or the pupae. This system should also work for other species with naked pupae. My friend does not put air holes in the container. However, I fear that they could eventually suffocate if sealed up for too long. So I open the container every so often. Or you could put in some air holes. Regal and imperial pupae can take freezing temperatures in the frij, but not for very long. Keep the temp above freezing. When it gets cold outdoors, that is the time to start the pupae's cold period. They need to be acclimated to cold. Keep them somewhere where they will gradually get cold over a period of at least a week, as it does outdoors, before putting them in the frij. In spring, take them out of the frij when it warms up outside. Put the pupae back into peat moss, in a flowerpot, inside a cage, outdoors. Water it often enough to keep them from drying out. The adult is able to crawl out of the peat when it hatches. Supposedly the pupa works its way to the surface, using its tail spine, just before the moth emerges. Remember that since regal and imperial moths have only one brood a year, and the moths fly in mid-summer, your pupae will sit there in the potting mix until July or August. For more info on winter storage of pupae, see Bill Oehlke's site: click here He supplies similar conditions in a slightly different way. A good description of how regal moths pupate, with photos, plus more rearing info, are on Adam Fleishman's site, which moved and I have to find where it went, link will return when I do. To see if a pupa is alive or dead, carefully poke it in the leathery area between two abdominal segments with something dull like your fingernail or the edge of a piece of paper. They hate this; live ones will squirm. Other clues: live ones weigh more (they sink in water) and are glossier than dead ones. All the native large saturniids overwinter as pupae, never as eggs. Things to see: Watching the larva actually shed its skin and become a pupa is a strange experience. The new pupa is not smoothly fused together over its surface - the head, antennae, and wings are still detached at first and the very soft pupa slowly pulses and scrunches its head into a concave position like a rubber toy being punched in. To see this, however, you must cut open the cocoon (maybe they could be induced to spin one against something transparent?), dig up the prepupa from the soil, or have allowed one to pupate in an empty container as described earlier for regal/imperial moths. There is danger of injuring the animal; also, before you disturb it, be sure the pupating larva has become a prepupa and is no longer able to walk. Otherwise, finding its cocoon gone, it will spin another one, using up a lot of its energy reserves. One spiracle is in front of the wings. To sex pupae, look at the underside near the tail. 4 abdominal segments below the wingcase, there is an area where the edges separating the segments seem to disappear or run together down the center. In females, this area is smooth and blank. In males, there are two little bumps right next to each other, where the genitalia will be. Also, the males' antennae are much wider than the females'. I am told that in luna moths, the larvae that are going to diapause turn brown just before they pupate, wander off the food plant, and spin darker-colored silk. Those that plan to hatch without hibernating stay green, make a cocoon right in the leaves, and spin lighter-colored silk. However, I am not sure this is completely reliable, as I have had cocoons do the opposite of what was expected. Some species spin a silk attachment tying their cocoon to the main twig, so when leaves drop in autumn it will stay up in the tree. One can indeed get silk from the cocoons of these "giant silk moths". However, the silk is a different grade from that made by the (unrelated) domestic silk moth raised in China.
  • Adult moths Emergence from the pupa is triggered by many factors, including temperature and day length. When the moth hatches, its wings come out all crumpled up; then the moth clings to something while the wings expand and harden. Thus, the moth will need something it can crawl up and hang from vertically or upside down. It must be able to hang freely, or the wings will harden crumpled up. Keep screen or sticks near the pupae for the moths to climb. Photos of a newly emerged moth showing the wings expanding. Warning: newly emerged moths squirt out a liquid that stains (it's the waste they made while inside the pupa). Keep the moth away from curtains/rugs etc. that you don't want stained. Adult saturniid moths do not eat. They live off their fat. They only live a few days. Females have a fatter abdomen (it's full of eggs) than males, and narrower antennae - the male's are wide and feathery. See a field guide for comparative pictures, or the photos here: Michael Cook's web site - excellent photos of both sexes - see the female's abdomen or here: male and female antennae compared (Photos by Mark Young.) After the male moth emerges, he flies off and starts searching for a female. When the female moth emerges, she crawls up a branch and just sits there. She is disinclined to fly until she has finished "calling". At whatever hour of the day or night is right for that species, the female "calls" for males by emitting pheromones. She sits still and lets her abdomen hang down so the pheromones come out. You can see a little brown/yellow thing sticking out the tip of her abdomen. Cynthia moth extending her pheromone thing (Photo by Mark Young.) Males can smell the pheromones from a long distance away, and fly upwind to find her. They will try to reach her and mate with her only as long as she puts off the smell. If she doesn't get a male the first night, she waits and tries again the next night. However, after a few nights, she will give up, stop calling, and flap around dumping infertile eggs. Mating in some saturniid species takes less than an hour; in others it takes many hours or all night/day. After mating, she flies away and lays her eggs on tree leaves. Many saturniids will mate with their siblings. If you can find a wild mate, that is better, to avoid inbreeding. Mating moths is the hardest part of rearing, and I'm not very experienced at it. I suggest putting the female inside a screen porch or large cage, and releasing the male in with her. There should be air flow so he can find her. The female's perfume is very powerful, and if the whole area is flooded with it, the male cannot pinpoint its source. You need a place that is totally free of the pheromone except for that coming from the calling female. I had to move pairs from a porch where many females had been calling to a "fresh" room before they would mate. Males will even come to an empty cage where females have been calling earlier. Males apparently use mainly their senses of smell and touch to find the female. Even when he gets close, it seems as though he doesn't use his eyes (I guess this makes sense - it's pitch dark) - he keeps relying on the scent right up to the moment he actually touches her. The male then gropes her body with the claspers on the end of his abdomen until he finds where to attach them. If you have no male, you can cage the female outdoors to attract a wild male. One can use a cage of half-inch screen that she can mate through but not escape from. However, you must retrieve her and her mate before dawn, or birds will eat them! A better method is to tether her inside an opaque container so that the male can find his way in but birds can't see them. The following design (method from Royce Johnson) has worked well for him even though the female is not completely concealed. Get a large black plastic funnel (as for changing car oil) and line the inside with paper or cloth for the moth to cling onto. Fold her wings up over her back, fold an index card or business card over them to protect them, and clip them shut with a clothespin. Wrap a wire around the clothespin and thread the other end through the snout of the funnel, to tether her underneath. Suspend the funnel upside down with the moth inside it. She is invisible except from directly below. (One might also try this method using a cardboard box, or a mailing tube.) What time the females call, roughly (info taken from Tuskes et al.): Promethea: late afternoon (not after dark). Cynthia: 10 pm til midnight (but I've seen them mate in the afternoon). Polyphemus and Io: 10 pm until midnight or 1 am. Regal: 11 pm until 2 am. Imperial and Luna: 1 am until 2 or 3 am. Cecropia: 3:30 am until 5 am (but varies). If your males emerge before the females, you can put them in the frij to keep them alive longer while waiting for the females to emerge. Warning - a frij at 40F is too cold; this seems to render the males incapable of normal behavior afterwards. 55F is better. Ultimately, though, if you want to be certain of getting a mating, you must have a fair number of pupae. Having several of each sex is not enough; you need enough so that there will be males and females emerging within a couple of days of each other. My guess would be about 20 pupae. You can put the mated female in a paper bag to lay her eggs, although she will beat herself to a frazzle trying to fly. She is less likely to get damaged inside a very large plastic container. I have used the big Rubbermaid bins (21" x 14" x 9"), and lined the sides with paper bag and the bottom with paper towel for her to crawl on. This allows you to release her after one night's worth of laying so you aren't stuck with all 200 or so eggs. (Number varies by species.) Another method is to clip her wings shut with a clothespin which is wired to a table or wall to hold her upright. Cover her wings with a card so the clothespin doesn't damage them. Put a piece of paper under her where she can grip it, and she will lay on the paper. (Method courtesy of Royce Johnson.) Things to see: The adult moth must escape the cocoon when it emerges. In polyphemus, the moth secretes a enzyme from its mouth area that weakens the "glue" attaching the threads together, then uses little blades on its "shoulders" to cut a hole in the silk. Luna moths make weak, thin cocoons, and do the same thing without the enzyme. Other saturniids simply push their way out; they make the outer layer of the cocoon with a hole at the head end, and the inner layer like a drawstring that can be forced open from inside. They also secrete chemicals that help the opening to expand. You can see their wet foreheads as they emerge. Insects were once thought to be cold-blooded, but in fact many thick-bodied, fast-flying insects can heat themselves up to at least 98F, even on cold nights, and remain hot for as long as they need to fly. This includes large bees, dragonflies, and sphinx and saturniid moths. In order for saturniids to fly well, the wing muscles (in the thorax) must be about the same temperature as the human body. A resting moth warms up by contracting the thorax muscles - you can see its wings vibrating as the muscles shiver. Catch a flying moth, fold its wings down, and feel the top of its thorax, then its abdomen, with your lips. You can feel the heat in the thorax! Saturniids are strong flyers when heated up, but clumsy when cold. Thus, the same moth can fly rapidly like a bat one night, then, the next morning, be unable to do more than flap awkwardly or fall when disturbed from its resting place. Read _The Thermal Warriors_ by Bernd Heinrich for more on insect body temperature. It is exciting to be able to go to a place where there are wild moths and see them come in to a female you have set out. Look at a moth under a stereo dissecting microscope, or a 10x magnifying glass, to see the beautiful scale colors. Enjoy!
  • FURTHER READING _The Wild Silk Moths of North America_, 1996, by Tuskes, Tuttle, and Collins, has thorough information on their biology and life histories, including rearing, plus photos of all the species and their caterpillars. Highly recommended.
  • ACKNOWLEDGMENTS While raising larvae and writing this, I was greatly assisted by Michael Collins, Chris Conlan, Royce Johnson, Bill Oehlke, Valerie Passoa, Eric Quinter, Mike Soukup, Robert Thorn, Bob Weast, and Paul Weaver. Thank you!!! :-) Thank you also to the many readers who have improved it with their photos and critiques.