What's growing in your garden? Many plants and trees in the garden play host to butterfly larva, or caterpillars. These (sometimes not so) cute critters happily gobble host plants until they are ready to transform into a butterfly. Why not encourage them to do so in your yard by planting host plants and raising the caterpillars yourself? Here's a brief primer on raising caterpillars.
(Editor's Note: This article was originally published on July 17, 2009.)
Whether you know it or not, you might have a classroom in your own back yard. Each season, gardens across the country play host to munching caterpillars and fluttering butterflies. Raising and releasing butterflies is an educational activity with lots of entertainment value… and it's not just for kids in the classroom.
It takes a lot of work to be beautiful! Butterflies go through three stages before they emerge as delightful adults (the fourth stage), sipping from garden flowers.
Egg Stage — A female butterfly seeks out a host plant and lays eggs (oviposit). With wings aflutter, she'll curl her body to deposit a few eggs on a plant before moving to the next. Eggs vary by species and are generally viewable to the human eye.
Larva Stage — In a few days, the caterpillar will emerge from the egg, often eating its way out. At this point the cat (caterpillar) may only look like a spec of dirt or a bird dropping. In the coming days, the cat will go through a number of instars or phases. With each phase, the cat will shed its skin, altering its appearance and becoming larger.
Pupa Stage — When ready to begin transformation, a butterfly cat will shed its last skin and form a chrysalis. This pupa is actually a part of the caterpillar and serves to protect the insect while it transforms to an adult butterfly.
Adult Stage — Now with wonderful wings, the insect has transformed to an adult, the butterfly that dances through the garden.
Many butterfly enthusiasts will tell you they raise caterpillars to increase their chances of survival. A myriad of predators threaten butterfly larva. Birds greedily gobble up entire colonies of cats in no time, while parasites such as wasps and tachinid flies slowly kill the hosts. Recent research underlines the dangers of parasitic wasps, discovering over 300 provisional species in existence. For others, the impetus is the wonder of the creature's transformation. This is particularly true in the classroom, where life unfolds before astonished eyes.
How to Raise Caterpillars
Do your homework
Before you jump into this enticing activity, be sure to learn all you can about what butterflies are in your area. You won't want to send away for any butterfly larva that are not native to your area or who's host plant you can't locate. It's likely you have host plants for different butterflies in your own back yard. Parsley and dill in the herb garden attracts Black Swallowtails; plantain, often considered a weed, hosts Buckeyes; butterfly weed is often planted as a nectar source, but also serves as a host for Monarchs, Queens and Viceroy. A chart below lists some of the common butterflies and their host plants.
When you see a butterfly eagerly fluttering at one of these host plants, you're sure to be witnessing her oviposit, or lay eggs. Now is a good time to collect the eggs, as they have not been exposed to any parasites. Bringing them in to safety at this stage offers a higher success rate then say, their last instar.
Choose a containment method
A fine screen attached to plastic containers makes a good cage. (TexasPuddyPrint)
Square zippered cages collapse for easy storage.
A pop-up type tent is designed to also serve as a flight cage and is popular in the classroom. (TexasPuddyPrint)
Even a reptarium can be used for containing caterpillars. (TexasPuddyPrint)
Plastic containers are easily organized by date of pupation and species. (Shelia_FW)
There are many different methods of containing cats, from small containers to larger custom-built nurseries. To help you decide which method is best for you, three Dave's Garden participants from the Hummingbird and Butterfly forum (available to paid subscribers) offer their advice.
One of the most popular methods of holding cats is to use disposable plastic containers. Easily cleaned, these containers offer a variety of sizes and shapes for different species of butterflies. When using small containers for a few small cats, debnes_dfw_tx cuts out the center lid of small plastic ware but leaves the rim. Then she attaches sheets of fine weave chiffon fabric to the lid rim. TexasPuddyPrint similarly cuts side and top windows, hot-gluing nylon/plastic screen material to the plastic. This allows for more air circulation. Here you can see that Shelia_FW finds these containers easy to keep organized with all her cats. She includes a note on each container, indicating how many cats are in each and ensuring that she does not throw out one with old leaves.
There are also a number of zippered mesh cages on the market for housing cats. Debnes_dfw_tx likes the 12-inch zippered cages. Small and inexpensive, these cages house up to 10 cats. If you are using these types, TexasPuddyPrint suggests putting the zippered end on the bottom or side to keep cats from pupating directly on the zipper. On the Butterfly and Hummingbird Forum, you'll find similar enclosures featured, including hampers and amphibian mesh terrariums. Also in this category are the pop-up cages that are a part of the kits popular with classrooms.
Customized cat enclosure such as boxes and wooden cages should be constructed in a fashion to allow for good sanitation. This generally calls for some sort of easily cleaned liner to catch all the frass.
A final method of containing caterpillars is to enclose whole plants. There are conflicting reports on whether this is a good idea. Some worry that predators might be living in the soil and therefore enclosing cats with the predators is trapping and dooming them to a certain death. For others, enclosing a whole plant or using a plant sock (to enclose a portion of the plant) offers the ability to provide a constant fresh source of the host plant. Many plants might not hold up to cutting or can be unpleasant smelling reports TexasPuddyPrint, who uses large netting enclosures on plants and cats at a remote location. "The netting also works great on a Skunk Vine… back at the ranch that is used by a moth caterpillar I occasionally raise. That vine really, really, REALLY has the most horrible odor…!" Some lucky souls have screened porches and can bring in as many potted plants as they need for host material. This method offers amusing results as adult caterpillars emerge and cling to the screen porch sides.
Each caterpillar species has it's own host plant, or family of host plants. Black Swallowtails host on the carrot family. In my garden they prefer dill, but in yours it may be parsley. Plant as wide a variety of host plants as you can to attract butterflies to your yard. Once you detect cats on the plants and brought in the plants, you'll need to keep a fresh supply of food for them. Methods differe here too. Monarchs have huge appetites, so may munch through milkweed leaves in no time. If you have plenty of plants and time, you can pick a few leaves and put in the cage. But remember that what goes in, comes out so you'll want to keep the cages clean.
Wet floral foam is the preferred method for prolonging the life of host plant cuttings in cat cages. It is favored because it will stay moist enough for the plants without putting cats in danger of falling in water (say from a vase or jar). Wet the foam and place it in a shallow container or wrap it in a plastic wrap. When it comes to inserting stems of tender plant material into the foam, it helps to first make holes in the foam with a toothpick. Shelia_FW describes her tidy floral foam method "I use the bottom of pudding cups as a cookie cutter on 1/2" wafers of wet floral foam. I then wrap it with Glad Press 'N Seal, and using a toothpick put holes in it for my leaves. I then run it under water to soak the foam."
Providing spots to make chrysalis (or not)
A "Jungle Gym" (TexasPuddyPrint)
Pupae attached to styrofoam (TexasPuddyPrint)
Styrofoam covered in material (Shelia_FW)
Once the caterpillar has pupated you may want to move it to a nursey, where it can safely emerge and hang to dry. If you have a larger cage, you have the ability to add sticks on which the cats can pupate. You may easily move these sticks to a nurser cage for emerging. If you're using the smaller plastic containers, you'll need to remove the pupa and place on some other item; some options include styrofoam, twigs, and cloth-covered boards. TexasPuddyPrint describes the process. "If one has gotten on a zipper or I find one in my yard pupating in a place where it could become food, I'll use a straight pin to pry off the cremaster/silk. I then use a dab of hot glue on the end of tooth pick to catch the silk and hold it to the toothpick. From there I'll push the toothpick into a piece of styrofoam or glue the toothpick onto a twig, wire jungle gym etc." She also warns not to touch the hot glue to the chrysalis as it could damage the caterpillar inside. Each species' life cycle is different, so research what butterflies you are raising to determine how many days the stages will take. You'll find you can then be prepared for a beautiful butterfly eclose in front of your eyes.
Most butterflies eclose in the morning and take some time to dry their wings. They need a warm day to fly so if you find yourself with a new one on a rainy day, best to keep it caged. While raising a butterfly is heartwarming activity, it is not without its gloomy moments. Often a butterfly will not emerge fully, or a caterpillar will die from parasite infection. But those who raise butterflies will tell you that the rewards are immense.
Know Your Caterpillars
Think twice before erradicating caterpillars on your plants. They just might turn into a beautiful butterfly. Here are some common caterpillars you might find in your garden, along with their host plants.
American and red elm, hackberry, Japanese hop, nettles and fals nettle
Chrysalis — The hard outer casing of the pupa stage, which sheds its last skin to reveal the chrysalis
Cremaster — The hooklike tip of a butterfly pupa, serving as an anchorage point
Cocoon — The pupa stage for moths, which is spun by the the larva
Eclose — To emerge as an adult from the pupa
Frass — The larva's excrement
Gut Purge — To evacuate the contents of the caterpillar stomach, generally a sign that the caterpillar is ready to pupate
Instar — A stage in the life of a caterpillar between two successive molts
Osmeterium — Often called stinkhorns, these glands emerge and emit a strong odor when a caterpillar feels threatened.
Proboscis — The elongated sucking mouth part of a butterfly
Pupa — The tranformative stage between larva and adult
Spiracle — An external respiratory opening
Tentacle — A flexible sensory appendage
Many thanks to Dave's Garden members and article contributors — TexasPuddyPrint, Sheila_FW, Debnes_dfw_tx and OPbirder — who shared information and pictures on their caterpillar rearing methods. These enthusiasts are not commercial breeders or collectors, but butterfly lovers.
Thanks also to those BugFiles Contributors — creekwalker, mellielong, TexasPuddyPrint, nanny_56, Todd_Boland, and LindaTX8 — for excellent caterpillar pictures.
I am one of those fortunate individuals who grew up on rural land that has been in my family for decades. My parents and grandparents were avid gardeners who gladly shared their love of gardening with me. Today I enjoy a small yard in town with my husband, two dogs and a cat who is in charge of us all.