Raising a Monarch Caterpillar

Raising Monarch Butterflies

Summertime and there are recycled glass jars on my kitchen counters filled with caterpillars. Monarch Butterfly caterpillars, smooth with vertical stripes in black, yellow, and white. Each end defined with a pair of graceful black "horns" that are shorter in the back, longer in the front.

Multiple jars, with caterpillars sorted by size. Small ones together, big ones together. And a bouquet of green Milkweed plant leaves, not for feeding, but with tiny glistening eggs waiting to hatch.

I've been doing this since I was 8 years old. My 10 year old daughter has known it all her life. She asks me each spring, "When are my Monarchs coming back?"

Usually by the end of May I've seen the first one. Lazing about my gardens, flying with the distinctive patterns of dart, soar, dart, loaf. Looking at the young milkweed plants coming up, checking for a tender leaf to dot with a single egg here, another one there.then on to the next garden, somewhere else.

I found an article today that I had written when I was 20. More pedantic than my current writing style, it still gives all the basic information one would need to successfully raise butterflies.

Raising a caterpillar is a way to illustrate the metamorphosis, or change of shape, that is common to all insects.

Larvae of the larger butterflies and moths may be collected by students or teachers by identifying and locating the appropriate food plant know to be preferred by that species. Eggs are tiny and more difficult to locate.

While it may be easy to pluck Black Swallowtail caterpillars off the garden parsley plant, or Giant Sphinx Moth worms from tomatoes, it is easier to use the Monarch caterpillar to illustrate the process of the changes.

Monarch caterpillars do not hibernate for the winter in pupa form as the other two examples do. The Monarch Butterfly has two generations of caterpillars each year, the second of which reach full growth near the end of September, enter the chrysalis state for about ten days, then emerge as adults.

To begin your search for caterpillars, identify the Milkweed plant which is the only food source of the Monarch caterpillar.

The plants are found in open fields and along roadsides, and are two to four feet in height. Each plant has opposing pairs of wide, smooth edged leathering looking leaves. Flowers are tiny and sweet scented, forming a ball shape, and seeds are fruited in elongated pods.

A simple test for identification is to break a leaf off the stem. Milkweed will leak a tiny drop of white sticky fluid.

Plants which are hosts to caterpillars may be identifiable by the well-chewed appearance of the leaves. And caterpillar droppings which look like dark brown dots may be visible on the lower leaves.

Female Monarch butterflies usually lay their eggs one at a time on younger, more tender plants. They seem to prefer plants which are in groups, and may avoid plants too near dusty roads.

Other insects may be found on the milkweed plants. Milkweed bugs are large, reddish beetles which hide near the tops in the smallest leaves. Ladybugs, earwigs, and Japanese beetles also are commonly found on the plants. Few other caterpillars seem willing to eat the milkweeds, but a variety of Tussock Moth may have as many as 20 or more caterpillars munching away on a single plant.

Monarch caterpillars are easy to differentiate from the hairy black and orange Tussock Moth. They are smooth skinned and striped with white, orange, and black.

Tiny, newly hatched caterpillars should not be handled. It is best to pick up any specimen under three quarters of an inch with a cotton swab or grass stem, so as to avoid injury to its delicate chitin. As one of the caterpillar's defenses against enemies is to coil up around itself and fall to the ground, it is a good idea to hold a flat container such as a tin pie plate under the specimen.

Larger caterpillars, which reach up to two inches in length when mature, may be gently handled. Holding a smooth skinned Monarch caterpillar may be compared to touching "an animated piece of velvet." (Gene Stratton Porter, Girl Of The Limberlost).

Pick the smaller leaves of the milkweed to feed the captives. If you cannot get fresh ones each day, put a supply in the refrigerator in a plastic bag with wet toweling.

Caterpillars should always be left with a good supply of leaves overnight as they do a fair amount of eating in the darkness. If not enough leaves are left, larger larva may prematurely pupate, or turn cannibal towards smaller caterpillars.

It is always best to keep caterpillars of similar size together, and to limit the number of creatures in each container to two or three.

For containers, glass peanut butter jars or pickle jars with metal lids are best. While glass may present a hazard in the classroom, the silk web which the caterpillars spin to climb up the slick sides does not effectively stick to plastic, and can cause the insect to fall to the bottom of the cage and die during the crucial transformation to the chrysalis.

Using a small screwdriver, punch holes into the metal lids with the sharp edges facing down into the container. Flip the lids over and flatten the edges with a hammer, but do not worry that the caterpillars will be harmed by the edges. The flattened edges form crucial anchors for the silk button to which the pupa will attach itself.

For fall generations of Monarchs, it is important to keep the containers of larvae in a cool place, and essential to so keep the chrysali. If possible, take the containers with the chrysali into an unheated garage or other sheltered place each night, being careful that the morning sun will not come and heat the jars.

This is necessary because the second, or fall brood, of the Monarch butterflies must not attain full maturity as adults, even though their shape is transformed.

To survive the cold northern winters, Monarch butterflies travel thousands of miles south to Central Mexico to hibernate, before returning to the north to create the next generation.

The coolness of approaching fall triggers a reflex within the chrysalis to delay sexual maturation in favor of the migrating impulse. Caterpillars which are not so treated will achieve full maturity and die within weeks of hatching, victims to the cooling climate.

The caterpillars themselves are easy to care for. Clean droppings out of the cage each day and insert fresh leaves. Take care not to handle the caterpillar enough to interfere with its need to eat, and eat, and eat, and shortly, it will turn into the waxy green chrysalis typical of the Monarch.

The third state of the life cycle of the Monarch is called the chrysalis stage, not the cocoon. A cocoon is spun by a caterpillar out of silk, often incorporating leaves or sticks. Since the Monarch transforms into its pupa by simply splitting its skin, this "naked" pupa is not a cocoon, but a chrysalis.

As the days pass, the chrysalis will gradually darken, until shortly before its hatching, it will be entirely clear, and the tiny, perfect wings of the adult visible within.

Do not disturb the butterfly while it is emerging from the chrysalis. Soon enough it will pump fluid into its expanding, but still soft wings. An hour or two after emergence, the wings will be tough enough that the insect may be coaxed to cling to a finger.

Since it usually takes a full day for wings to dry enough for strong flight, the butterfly may be kept overnight, either in an adult holding cage, or resting on a carefully selected perch. If the day is cloudy, it may be advised to keep it a second day, but more than that may harm the butterfly.

To release the butterfly, either take it outside and place it on a brightly colored flower, or hold it on your outstretched hand.

Glossary:
Abdomen: the soft body section of the insect,
Chitin: the tough exoskeleton of the insect which contains all soft inner parts.
Chrysalis: the naked pupa of a butterfly which is not enclosed in a cocoon made of silk and leaves or sticks.
Cocoon: the silken covering woven about the larva by itself before it pupates. This serves to protect it from enemies and the weather. Moths commonly weave cocoons before pupating, butterflies do not.
Larva: the caterpillar or second stage of the insect.
Metamorphosis: the changes in shape which insects undergo during their life cycle.
Migration: the regular movement of a group from one area to another.
Molting: the shedding of the outer skin which has become too small for the growing larva, since chitin does not stretch.
Overwintering Sites: the areas in Mexico where the Monarchs gather to survive the cold northern winter weather.
Prolegs: the legs located on the middle section of the caterpillar, one pair per section. They are not true legs, as they are not present on the adult insect.
Pupa: the third stage of the insect where, although no outward change is visible, the larval insect metamorphs into the adult.
Silk: the fine cobwebby thread which can be spun by a caterpillar.
Spiracles: the breathing pores of the insect, located on the sides of the abdomen of both larva and adult.
Tagging: the placement of a tiny, pressure-sensitive label with a return address and a unique number on the right wing of individual Monarchs.
Thorax: the middle section of the insect, immediately after the head.
Truelegs: on a caterpillar are the three shiny, chitinous pairs of legs at the front of the caterpillar.