Butterfly Gardening and Rearing

A Children’s Butterfly Garden with a Lath House for Planting Seeds at the Allen School, Bonita, CA. Designed and built by Monarch Program’s Director David F. Marriott and Interpretive Specialist Seiko Alvarado.

Rearing Monarch Butterflies

Monarch butterflies (Danaus plexippus) are a difficult species to rear to adulthood in captivity.  They are an easy target for various predators and diseases.  Most people believe it would be easy to rear monarch caterpillars on milkweed (Asclepias species) and they would magically become adult butterflies.  Not true.  In the wild female monarchs often oviposit up to 400 eggs.  However, usually only two or three will survive to adulthood and mate to continue future generations.  Insects are an integral part of the food chain, for vertebrates and invertebrates.

Egg (0vum)

Monarch Egg, © Bill Howell (click the image for a larger view)

Many butterfly eggs will “hatch” in 6 to 10 days (depending on the season, weather, and species).  People successfully rear butterflies from eggs by learning from numerous failures.  Fresh plants and a sterile environment are very important for newly emerged larvae.  Harmful diseases, parasites, or predators may not be apparent until later instars, or the pupa stage.  Cleanliness, fresh-healthy food plants, and experience are all necessary to rear butterflies from eggs to adults.  Here are two important suggestions:

1. If eggs are collected from your garden or from the wild, cut the base of the leaf with the egg(s) and place the leaf on its host plant inside a paper cylinder taped to the plant.  The cone-like cylinder will help you keep track of the newly emerged larvae and prevent the eggs from falling off the leaves.  If you are using cuttings of the host plant, rinse the leaves with cool water, dry with paper towels, and place them into a jar of water with paper towel stuffed into the top of the jar and tape a cylinder around a stem(s) of the cuttings.  Place the host plant with eggs indoors (no direct sunlight).  Check the plant regularly for spiders and ants.  Move the larvae with the tip of a paintbrush when they are about a week old to fresh leaves on a potted plant.  A twisting motion of the paintbrush helps pick up and deposit the larvae on the new leaves.  Continue rearing the larvae on live plants in a cage.  Note: If the host plant cuttings with the eggs begin to dry before the larvae emerge, cut the entire leaf/stem and place on top of fresh host plant cuttings.
2. If your eggs are on a potted plant, keep the plant away from predators as described above.  The soil in the potted plant needs to remain as dry as possible without harming the plant.  Moist soil and caterpillar droppings (frass) can eventually produce bacterium.  Some viruses will infect all larvae in the immediate area.

Caterpillar (Larva)

Monarch Caterpillar, © Bill Howell (click the image for a larger view)

Butterfly larvae molt (shed their skin) four times forming successively larger larvae called instars.  The fifth molting produces the pupa.  Fourth instar larvae are often recommended for children/family activities and classroom projects because less food plant is needed before a larva becomes a pupa.  Here are some tips on rearing butterfly caterpillars:

1. If larvae are feeding on a potted plant, make sure the soil is not wet enough to produce mold.
2. Frass (caterpillar excrement) should be removed often in order to ensure a healthy environment for the larvae.  Cages/containers should be cleaned with 20% bleach, rinsed and dried in the sun at least once a week when numerous larvae are reared (25 or more per cage).
3. Many butterfly larvae need a place to hang in order to pupate properly.  A cardboard top or various twigs placed in a cage or container works best.  This will help discourage the larvae from pupating on the sides of the cage.

Chrysalis (Pupa)

Monarch Pupa on left is close to emerging, © Bill Howell (click the image for a larger view)

The adult butterfly metamorphosis occurs in the pupa stage.  This magical transformation from pupa to butterfly usually takes 10-15 days (depending on climate and species).  Some species from the swallowtail family, Papilionidae, may take years to emerge.  Below are five items to consider for caring for a pupa.

1. Make sure the pupa is at least ten inches above the bottom of the cage/container.
2. If a larva pupates on a vertical smooth surface, tape netting or paper towel under the pupa so the butterfly has something to hang from when it emerges.
3. Wing patterns and colors can be seen through the pupa casing up to 30 hours before the butterfly emerges.
4. When the butterfly emerges, it will usually hang from the empty pupa casing.  Don’t be frightened by the blood colored liquid it secretes, it’s called meconium (“urine”) and within a day it’s clear.
5. If the freshly emerged butterfly is not allowed to hang upside down for about 20 minutes it may have problems – especially if it falls to the bottom of the cage within a few minutes.  You can use your fingers and “re-hang” the butterfly but if it falls again and again, it probably has a virus.  Butterflies that do not survive should be placed in the freezer for 5 days – they are cold-blooded and just “fall asleep.”  The dead specimens can be used as a classroom study project (looking at butterfly body parts through a hand lens, microscope, or just displaying the wing patterns and coloring them).

Adult (Imago)

Overwintering butterflies, such as monarchs and some of the brush-footed family (Nymaphalidae) may live eight or nine months if they emerge as adults from late August through the month of October — otherwise they live an average of four weeks if they emerge during other months.  Our small butterflies, such as the blues and hairstreaks usually live for two weeks.  Whites and sulfurs often survive more than two weeks.  A butterfly’s diet includes only fluids: mainly nectar from flowers, pollen, and minerals in water.  They also enjoy juice from rotten fruit or vegetables, moisture from animal sweat, and animal excrement or carcass.

Adult butterflies for family or classroom projects should be released within 8-24 hours after emerging.  Keeping the live butterfly longer may affect the insect’s longevity and defeat the purpose of rearing a butterfly to be released into the wild.  Do not try to feed the butterfly.  They do not take nectar/liquids until the day after they emerge.

We recommend that children, and people of all ages, search for caterpillars in the wild and take them home or to the classroom to watch their metamorphosis.  Be sure to only feed the caterpillars the plant that they were feeding on when they were collected.  Most all butterfly caterpillars use only one plant species.