How to Raise Butterflies

One of the joys of summer is watching butterflies fluttering around flowers in meadows and gardens. Some butterflies are brightly colored and have spots. spec-kles, or stripes on their wings. As they drink the sweet juice or nectar of the flowers, they seem more like flying flow-ers themselves than like insects.

Butterflies are classified as Lepidoptera, which means scale-winged. The scales give their wings an appearance of velvet and rub off like fine dust if touched.

Butterflies don’t start out in life with wings but must work their way through four stages: egg, caterpillar (larval stage), chrysalis (pupal stage), and winged adult. This process is called metamorphosis, a Greek word that means “change of form.” It is an amazing process to watch, and you can do that by raising a butterfly yourself. And then you can have the satis-faction of releasing your butterfly to polli-nate flowers. Butterflies are valuable polli-nators, as we shall see.


Monarch butterflies are well known in many parts of the world because milk-weed, eaten by their young, grows in so many places. You can recognize Mon-archs by their orange wings veined in black, with black margins decorated by two rows of white dots.

Monarchs are among the few migrating butterflies, flying incredible distances. In autumn they migrate from eastern and central United States and southeastern Canada to winter in central Mexico. There, they rest on trees by the hundreds of thousands. As winter ends, they mate, fer-tilizing the females’ eggs. Then, flying northward, Monarchs arrive in the southern states in spring. Most of those reaching the northern states by summer are females that have been lay-ing eggs along the way. (Some of their offspring reach up into Canada—the southern parts of Ontario and Quebec, and all of New Brunswick and Nova Sco-tia.) Almost all males die on the way north from the wintering grounds. Western Monarchs are found in greatest numbers west of the Rocky Mountains. They winter in California, along the coast from Monterey to Los Angeles.


The first step in raising Monarchs is to find their eggs. For that, you must look for milkweed plants growing in meadows, weed-filled lots, or along roadsides. You may see a female Monarch searching too, since milkweed leaves are the only food her young will eat.

If you are lucky enough to see her flying from leaf to leaf, follow and ob-serve. Once an egg is laid, her interest in it ends. And after all her hundreds of eggs are laid, her own life will fade away. She may have flown thousands of miles and her fragile wings may be tattered and worn. Or she might be a young butterfly recently born on the northward migration route. Usually she deposits only one egg un-der each leaf that she chooses. You will soon understand the advantage of that.

It helps to use a magnifying glass when examining the underside of the leaves be-cause the egg is as small as the head of a pin. Magnified, you can see that it is cone-shaped, ribbed, and greenish white. Without a magnifying glass it’s easy to mistake smooth round droplets of hard-ened milkweed juice for eggs. These will not hatch. Cut at least one inch of the leaf sur-rounding the egg and bring it indoors, but not into an air-conditioned room.


To keep the piece of leaf fresh, place it on a moist paper towel in a tinfoil tray or on a plate. Use paper towels that have no chemical odor when wet.

A plastic bag wrapped around the tray also helps keep the leaf from drying out. A polyethylene bag is the only plastic we have found not harmful to caterpillars.


About four days after the egg was laid, or longer in a cool place, it is ready to hatch. A black dot can now be seen at the tip
of the egg. This is the head of the baby caterpillar. Soon his head pokes through a hole he eats in his “eggshell” and gradually he eats his way out. (I say “he,” but we can’t tell male from female in this larval stage. To find out, we must wait for the butterfly.) After the new-born caterpillar has made a first meal of his empty “shell,” he would eat any eggs that were nearby, so it’s good that the mother tends to lay her eggs on separate leaves.

Next, the tiny caterpillar begins eating the soft part of the leaf, later nibbling small holes through it. In a few days he has doubled his size. Now yellow, white, and black stripes ring his body. He spends all his time eating, resting, and eating some more. You have to keep him supplied with fresh milkweed leaves.

Various sized caterpillars share milkweed leaves in an incubator tray. The girl is about to transfer a half-grown caterpillar to the large rearing cage (in background) where she is raising a few dozen Monarchs.

Puff the plastic bag to trap air inside. He doesn’t need much. Air enters his body through a row of small holes along his sides, connected to tubes that deliver it to all his organs without the benefit of lungs. After about a week in the incubator tray, the caterpillar is large enough to transfer to a rearing cage where he will have more room to move around and later go into the next stage of his meta-morphosis.


Various types of rearing cages can accom-modate a few Monarchs at a time. The most elaborate is one my naturalist hus-band developed, using four pieces of wood. A narrow jar of water holds a stem of milkweed leaves and is bound to the frame by a rubber band. A plastic bag, whose opening fits tightly around the base, keeps the caterpillar inside and the leaves from drying.

For those with less time or skill in car-pentry, a jumbo-size glass jar will do very well, as many teachers have discovered. Inside, place a small jar of water tightly covered with a sandwich bag. Poke a hole to insert a stem of milkweed leaves. Or else, pour clean sand in the small jar and insert the stem. Keep the sand wet but not enough to drown the caterpillar, should he fall in. Tie a double layer of gauze over the top of the jumbo jar. Another type of cage is the cylinder made of fine screening about a foot high. Roll the screen so that the bottom fits into a large jar lid or the bottom inch of a big tin can. Tape the overlapping sides. A plate or tightly fitted plastic bag serves as a top.

If all else is unavailable, use a half-gallon milk carton. Simply cut out four side panels and the top. Inside, place a jar of milkweed leaves and the caterpillar, then lower the carton into a plastic bag and tie a double layer of gauze over the top. Now you have a habitat which can sup-port one, two, or three caterpillars. To raise more, you might make use of an empty aquarium covered by screening. Change the milkweed leaves every other day or so. The caterpillar must eat enough to nourish himself now, and also in his next stage when he won’t eat at all. You will notice dark droppings that re-semble peppercorns. This is the caterpil-lar’s waste and can be removed when you change the leaves.

If you see the caterpillar wriggling out of his skin, don’t be alarmed. His skin doesn’t grow larger as he grows. The tightness triggers a gland to release a slippery fluid between his old and new skins and he sheds the old. This is called molting and he will do it five times. After the fifth time he will no longer be a cater-pillar. To prepare the cage for that remarkable event, place a twig in it with a horizontal branch as long as the space allows—from which he will be able to hang.


Having eaten for two weeks or more, the caterpillar is fully grown, about two inches long. Now he searches for a safe place to change into his pupal form. He must hang so that when he emerges as a butterfly, his wings will have room to ex-pand without touching anything else. He crawls around to find just the right spot. Although nearly blind, seeing only light through three simple eyes on each side of his head, he is able to feel his way around. As he moves, he spins a safety line of silk from a fine tube, called a spinneret, on his lower lip. This silk will be an important help as he attaches him-self to the twig.

You will know he has selected his spot when he stops wandering. After a while he weaves a tiny button of white silk and walks over it until the tip of his abdomen reaches it. Now he clamps his two rear legs into it. He seems in no hurry to end his caterpillar life. Very slowly each of his remaining legs loosens its grip on the twig and lets go—four pairs of fleshy legs on his abdomen and three pairs of jointed legs in front. As the last support is gone, his body swings head down, suspended. Already his caterpillar organs are dying, but out of that death will come his won-derful new life. He hangs peacefully in a “J” position for a day and a night, his long black feelers limp.


Finally he is ready to molt for the last time. Stretching himself again and again, he pushes the skin away from his head until it splits at the back of his neck and rips up his back. His rippling movements push his skin upward, and along with it, his face and legs. Underneath is a soft green blob.
Right now he must work very hard. What happens in the next moment will tell whether he lives or not. Under his skin at the end of his abdomen is a shiny black stem called a cremaster, with micro-scopic hooks in it He must hook this into the silk button, which he cannot see or feel, before throwing his skin away. If he can’t do it, he will fall and die.

After successfully completing this diffi-cult acrobatic feat, he twists until the cre-master is tightly hooked and his skin drops to the ground. In an hour, the green blob becomes smooth and harder. In a few hours, little gold dots appear in the chrysalis. They aren’t real gold, but they might fool al-most anyone. Yesterday he was a caterpillar and today he’s a beautiful jade-green chrysalis, which, however, should not be handled. A chrysalis is a butterfly pupa. Pupa means “doll.” and an insect in this stage doesn’t move. But, although he seems to be resting, many changes are going on. Butterfly cells were stored inside him from the time he formed within the egg. Now they begin to grow and multiply. The chrysalis will hang for nine to fourteen days. His development is slower in cool places. faster in warm. About one and a half days before the butterfly breaks out, you notice a change in the chrysalis from green to teal blue and a gradual darkening. Twelve hours later it becomes transparent enough to see orange wings.

About one and a half days before the butterfly breaks out, you notice a change in the chrysalis from green to teal blue and a gradual darkening. Twelve hours later it becomes transparent enough to see orange wings.

The butterfly clings to his empty chry-salis shell as his muscles pump blood into his soft, crinkled wings. Within eight minutes they expand to full size, but they are still damp and must dry before he can fly. He coils and uncoils the two halves of his long sucking tube to match their notches and connect them into a single tube. Otherwise, he won’t be able to drink. For an hour or more he clings to his shell, clasping it with his long legs. He seems to have only two pairs of legs. but a smaller pair is folded in front. As he waits, a few red-brown drops fall from the end of his abdomen. These are the wastes that were stored while he was a chrysalis.

When he opens his wings you can tell he is male by a small black dot on each hindwing, marking the male scent glands. Can you see that the top Monarch below is a male? The other butterflies are either females or their wings are folded, cover-ing the males’ black dots. Release the butterfly outdoors the next morning unless it is raining. In that case, he might accept a sip of sugar water from a saucer to tide him over.

Outside, he’ll circle in the air, fluttering higher to get his bearings. Monarchs that hatch in spring and mid-summer will mate and the females lay eggs, but those that hatch in late summer and autumn wait to mate and lay eggs until after win-ter. They are the ones that migrate south, finding refreshment stands of flowers along the way.

A butterfly sips the nectar of flowers the way you sip soda through a straw, but the “straw” is part of his or her mouth and is called a proboscis. Kept neatly coiled until needed, he extends it deep into flowers. Grains of pollen stick to it, rubbing off on the next flower he visits and fertilizing it, so that its seed can grow into new plants. Thus, without knowing it, butterflies “pay” the flowers for their food by per-forming a necessary service—pollination. By raising butterflies, you are helping too.


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