indoor rearing of cecropia


Hyalophora cecropia larvae in their final instar are spectacular for both their tremendous size (approx. 11cm / 4.5in.) and beautiful coloration.

Many people come across these monsters feeding on fruit trees in late summer.

Cocoons and ova are available for purchase. Click on cocoons for a price list.

Photo courtesy of University of kentucky

Although the rearing of this species on open, indoor displays is labour intensive, the majesty of these caterpillars makes the effort worthwhile. Anyone interested in close observation of larvae, in protecting larvae from parasitization, or in introducing others to the fascinating world of insects should consider the option of indoor rearing.

The breeder, beginner or advanced, can begin with any of the four metamorphic stages: 1) adult moths, 2) ova, 3) larvae, 4) cocoons.

In this article 1) sources for each metamorphic stage are explained, 2) an indoor rearing technique is described, 3) a general facts list is provided, and 4) some suggestions are offered.



Photo courtesy of Mike Soroka

Gravid females, distinguished from males by their much narrower antennae and heavier bodies, are attracted to and easily captured at lights in the early hours of darkness. Ultraviolet (black light) or mercury vapour lamps radiating outward and upward in the vicinity of host food plants work especially well from May-July, the flight time for this species. Biological supply houses, individual dealers, or Home Lighting Centres are good sources for these light fixtures. An old white bed sheet, secured vertically or horizontally below the light, aids in the reflection of rays and also affords the moths a resting place. A visiting moth can be hand picked or netted for capture.

Virgin females, obtained from one's own reared or purchased stock or from cocoons found in the wild, mate readily in captivity. Some breeders like to "tie out" or tether the females. One makes a half hitch loop near the end of a soft cotton string, one to two feet (25-50cm) long, and slides this loop over the female's abdomen up to the juncture with the thorax. The knot is gently tightened and secured with a second half hitch. Working with a partner facilitates this process. An assistant can hold the closed-winged moth with its legs up and grasping a pencil while one slides the loop up to its proper resting place. Once the female has been secured, she can be tied out after dark by fastening the other end of the string to a small branch of a tree. Males often do not arrive until after 4:00 am so "waiting up" is impractical. One must, however, check the female before daybreak or the birds will be chirping, "Thankyou, thankyou very much!" The couple should not be separated, just protected from predation. Snipping the branch and bringing the pair indoors is recommended. The moths will disengage before nightfall.

Cage matings require less work. The female is placed in a cage with a mesh small enough to prevent her escape but large enough to allow mating with a wild male. Square openings of at least 1/2 inch or 1.25 cm work well. The cage, which need not be much over one cubic foot, should be checked before day break. I fashion 14 inch high cylindrical cages out of 1/2 inch hardware cloth and use a dinner plate for a lid over the 8.5 inch diameter top.

This beautifully marked pair are copulating inside a screen cage.

The pair usually remain coupled for up to twenty hours and separate naturally in the evening.

The female will begin laying eggs almost immediately so it is wise to keep an eye on her and move her to a bag as soon as pairing is over.

Photo courtesy of Mike Soroka


To obtain eggs, place the gravid female in an inflated brown paper grocery bag. Fold down or twist close the top. Moving the female to a new bag every day or two and keeping egg batches separate ensure the larvae from each egg batch will emerge within a short hatching period. The used bag is then cut into small patches around the ova and these slips are placed side by side, egg side up, in a dry sandwich tray or small, wide-mouthed container. Thirty to one-hundred eggs can be handled in a single tray. No food is placed in the covered receptacle until the small black larvae are seen ten to twelve days later. They usually eat a portion or all of their eggshells and sometimes wander for a few hours before congregating on the food supplied after emergence.

Ova can also be obtained from dealers. Postal shipment should not be a problem as the eggs incubate for ten to twelve days at room temperature. If the eggs arrive in a protective sleeve, i.e., aquarium tubing, turkey quill, etc., they should be gently removed from the protection and allowed to rest on the dry bottom of the hatching container.

Trying to find cecropia ova in the wild would be much like looking for a needle in a haystack, but I have found them in groups of 4-5 on the underside of elderberry leaves in areas of high cecropia populations (Secaucus, New Jersey, 1960).


Larvae generally are not shipped in the mail, but they can be "picked up" from a breeder if you are close. It is not too difficult to find wild caterpillars in areas of abundance. Since the larvae are voracious eaters, missing foliage and droppings on the ground invite plant inspection by collectors and predators. Unfortunately this species is highly susceptible to parasitic wasps, especially in the fourth and fifth instars and high percentages of "found" larvae are hopelessly parasitized. In such cases the larvae grow and spin cocoons, but wasps are all that emerge the following spring. Look on the underside of host plant leaves to find smaller, parasite free larvae.


Cecropia cocoons are huge compared to those of lunas, ios, polyphemus, prometheas, etc. and they are usually affixed length wise to and near the base of host shrubs or neighboring plants. These can be found before or after leaf drop. Those that are spun up higher on the tree are quite noticeable after leaf drop. Rats and mice also find them and feed on the pupae. The cocoons are rugged and can be removed from stems by carefully pulling from the top down. When the cocoons are attached to narrow/upper stems, clipping is appropriate. The pupa is protected in a denser, inner cocoon, considerably smaller than its looser, baggy, outer wrapping. A gentle hefting and shaking can be used to determine the health of the pupa. A very light rattling or no sound or movement at all indicates parasitization or disease. A healthy pupa has a noticeable weight and will offer a dull thud upon shaking.

Many dealers in North America offer cocoons in the fall, winter, or early spring. Cocoons may be winter-stored out doors in cages that would protect them from predation by rats, racoons, skunks, etc., or they may be kept in refrigerator crispers until the spring. Three to four weeks at room temperature coupled with at least twelve hours of daylight/daily will often trigger emergence.

The emergent moth exits the top of the cocoon and must find a place to "hang" so fluid can be pumped into wing veins for expansion. An emergence box with screening or cloth sides for climbing should be provided.


In the fall of 1996 I had great success with cecropia larvae which proved to be quite sedentary and content to remain near the tips of pin cherry (Prunus pensylvanica) stems set up in open, indoor displays. The displays were used for educational purposes in P.E.I. schools.

Five or six stems were inserted through 1.5 centimeter diameter holes in 2" x 8" spruce scraps which I picked up for the asking at a nearby construction site. The spruce was cut into octagonal shapes and set to float on seven centimeters of water in 11.4 litre ice cream buckets. The leafy stems projected at least 30 cm above the container tops.

A gravid female from a cage mating had been placed in a brown grocery bag and fifty eggs laid on July 21-22 were moved, still affixed to paper, to a three litre, wide mouthed, plastic candy jar. Larvae began emerging on the morning of August 1. Two four-inch-long pin cherry stems with three to four leaves attached to each were placed in the covered jar after the larvae emerged. The caterpillars had all moved to the leaves and begun feeding by evening. No coaxing was necessary.

To help keep the leaves fresh, I wrapped the cut end of each stem in moist tissue and prevented a moisture build up in the candy jar by enclosing the tissue wrap in a plastic sandwich bag, collapsed and secured with a twist tie. I was also concerned with toxins possibly coming from the cut stems which were allowed to lie flat on the bottom of the container. Pin cherry bark contains some poisons. My concern, however, may have been unwarranted.

After three days of larvae growth, I removed the stems with caterpillars attached to the indoor display previously described. The sanwich bag and moist tissue were removed and the old stems were laid on top of and perpendicular to the new food. The larvae soon moved to the fresh foliage.

Please note: My open displays were in a small 8' x 8' room where window and door were kept shut. The evaporating moisture from the open buckets maintained a humidity essential for caterpillar health. Indoor air is normally too dry for such a display when caterpillars are small and would easily desicate. For the early stages, it is best to use a closed container unless you can maintain a proper humidity.

As the larvae grew, their numbers were divided into smaller groupings for each display. Food changes were accomplished by lifting all stems from the spruce support, laying the old stems on a newspaper covered, flat surface, raising and rinsing the spruce, dumping the old water, rinsing the container, adding fresh water, replacing the spruce, inserting fresh stems and finally transferring the old stems with caterpillars to the new displays.

The old stems were carefully laid across the tops of or inserted vertically among the new stems. Care was taken to avoid transfers during molting, but occasionally one or two caterpillars would be slightly ahead of or behind their peers. Quiescent caterpillars were moved as carefully as possible and none were lost due to molting or any other problems. Old stems were lifted and discarded once the larvae had moved.

Food stayed fresh for six-seven days and was replaced as leaves were depleted. Larvae spent approximately one week in each instar except for the fifth instar which lasted slightly more than two weeks. Food had to be replaced more regularly as the larvae grew. During the final instar, food was being replaced every two to three days to stay ahead of 5-6 larvae on each display. Indoor temperatures stayed fairly constant, between 68 and 75 degrees F.

Fresh food was always selected from lush plants. The cut stem ends went immediately into water to avoid any wilting. To cut down on repeated food hunts, I gathered more than needed and kept the food fresh by placing it outside in a shady location with cut ends immersed in a few inches of water.

No special provisions were made for the spinning of cocoons. Some of the larvae spun at the base of the stems just above the spruce float, but many spun up in the leaves above the container rim. I let the larvae have at least two weeks in the cocoon before moving them into cold storage. Cooling before pupation occurs may destroy all your efforts.

A big surprise was that no larvae attempted to leave the uncovered buckets. They rarely descended below the bucket rims except to spin cocoons. It is reported that the larvae of the domesticated bombyx mori have been so conditioned by the constant human provision of fresh food that they will starve themselves rather than crawl any distance for fresh leaves. Perhaps the cecropia larvae, which never had to move far for food, were also responding to a bit of conditioning.

Another sampling of larvae from the same ova group (July 21-22) was raised outdoors in a large, vertical sleeve until September 6. These larvae still had ample food in their enclosure when I brought them in, but all the upper most leaves had been eaten and the caterpillars had done quite a bit of walking down branches and the trunk to access foliage on lower branches.

When these caterpillars were brought indoors and set up on the dispays, the larvae continued walking, frequently crawling down the stems and up and over the sides of the containers. I had to cover all these set-ups with inverted buckets for containment. Side by side on a newspaper-covered plastic floor mat were open displays of sedentary cecropia and covered buckets of discontented crawlers.

Several displays of the sedentary group were taken into schools and left uncovered. Fascinated students gently stroked the larvae with their fingers. The unobstructed viewing of the tireless spinning was also a special treat. None of the larvae wandered.

Teachers or breeders who supply schools, may want make use of this technique. A word of caution, however: Make sure you advise the custodian as to what is lurking in the attractive greenery on the teacher's desk.


COMMON NAMES: Cecropia, Robin moth

RANGE: Eastern North America to the Rockies, Canada to the deep south

SIZE: This is North America's largest saturniidae with a 5-6 inch (13-15 cm) wingspan. Caterpillars achieve lengths exceeding 4 inches (10 cm)

FIRST INSTAR: black with black dorsal and lateral tubercles
SECOND : yellow-green with black tubercles
THIRD : green with four red thoracic tubercles, yellow dorsal and blue lateral tubercles
FOURTH : identical to third
FIFTH : green with four red-orange thoracic tubercles, yellow dorsal and blue lateral tubercles, a gray oval surounding each spiracle

COCOON: Cocoons are of two types:
1) a large, loose, baggy structure, with a rounded bottom and a tapered neck;
2) a smaller, denser oblong structure with a tapered neck and bottom. In either case there is an oblong, inner cocoon of relatively tight construction. Cocoons are always affixed longitudinally to a stem and are generally red-brown or brown, although some are gray or even a drab green. Compared to cocoons of other North American species, these are monsters, up to 4 inches (10 cm) long and 2 inches (5-6cm) wide.

FLIGHT TIMES: May to July, primarily in June. In southern states cecropia have flights recorded from late April to early August.

LIFE SPAN: One year. This species is single brooded and spends the vast majority of the year in the cocoon/pupa stage. Adult life: six to eight days Egg Incubation: ten to fourteen days Larval Development: five to eight weeks

FOOD PLANTS: Cecropia accept a wide range of food plants, many of which transport and hold water very well: pin cherry, choke cherry and other Prunus species; Manitoba maple or box elder; willow; apple; lilac, pecan in the south, elderberry, American elm, green ash, southern bayberry or wax myrtle, red maple, poplar, Amelanchier, Crataegus, and Viburnum species.

TREE DAMAGE: Generally not regarded as a pest, but in high population densities will defoliate smaller shrubs, i.e., Manitoba maples in the prairie provinces. Females generally lay a single row of four to five eggs on the underside of a leaf.

REARING: Fresh or cut food is accepted. Avoid overcrowding and protect from parasitization. A clean sleeve or cage will minimize risk of disease. Warmth seems to stimulate growth, but avoid overheating.

DEMAND: Popular in Europe and North America. Research regarding distribution diversity, food plant influence on coloration, pheromone analysis, intergrades with other species of Hyalophora, etc., tends to go on at various universities and in private studies. More zoos are setting up live insect displays. Life histories and art displays create demands. Schools seek life histories and live displays for educational purposes. Excellent in salads. I hope not!

SUGGESTIONS Large plastic buckets can usually be had for free or for a minimal charge from ice cream parlors, meat counters in grocery stores, or fast food outlets that use large amounts of cooking oil. The 2" x 8" spruce was especially effective in keeping the stems upright and in keeping the caterpillars out of the water.

Indoor rearing of cecropia is very labour intensive as the larvae have enormous appetites in the final instar. Large numbers are better handled outdoors on live food in some sort of protective sleeve or on shrubs in a cage. Reemay, a spun-bonded garden cover, or light fibreglass screening is excellent for bag-like enclosures. If parasites are a problem, then moving the larvae indoors for the last two instars may be the only solution.

Pin cherry, which is a small, sun-loving tree, tends to have upward reaching branches. Such trees lend themselves to capping or complete foliage enclosure. It is not too hard to bend the thin trunk of a fifteen foot tree so that the crown can be covered with a large, light bag.

Once the tree has been capped, the caterpillars inserted, and the open end tied off securely around the trunk, the tree can be released from its hand grip or tie down position to return to its normal stature. Fifteen large larvae in a twelve foot sleeve is plenty unless you want to flirt with disease or trouble yourself with frequent changings.

Cecropia are choice hosts for some parasitic wasps. Don't let the larvae completely strip the tree- "all the better to see you, my friend"- or you'll be inviting the wasps, hornets, and birds. Such a practice wouldn't help the tree much either.

A capped tree, with the bottom of the enclosure within easy reach, also makes for easy cleaning and frass should be removed every few days.

Take the time to share your interest with a friend or school children. An open, indoor display of Hyalophora cecropia won't go unnoticed.

Bill Oehlke
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