Raising butterflies and moths
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Why Raise Butterflies?
There are few activities as rewarding as raising butterflies. The transformation of a tiny caterpillar through 5 instars, followed by the pupa and finally the beautiful adult butterfly (or moth) may even seem miraculous.
Where to find caterpillars
Depending on the season, where you live, and how much time you have, finding your own caterpillars may be a rewarding task. The best way to find caterpillars is to look for plants that are known host plants for local butterflies and moths. Consult field guides to find this information. Some good host plants to find caterpillars include:
If you are short on time or if the season is wrong for caterpillar hunting, there are several companies that supply caterpillars. Painted Lady caterpillars are particularly easy to keep because you can buy a growth medium for them, which will eliminate the need to find fresh host plant leaves for them every day. However, there are drawbacks to raising caterpillars this way. In particular, students do not get the full benefit of learning how important it is for caterpillars to have the correct host plant to eat. Nevertheless, raising Painted Ladies on growth medium is still a rewarding experience for the students, and is less dependent on the season outside and which leaves you can find.
Butterfly larva of the well-loved Monarch butterfly can be purchased from an organization known as Monarch Watch (www.MonarchWatch.org). These caterpillars are a favorite for a lot of classrooms because of their bright colors, and because so many people love the Monarch butterfly. The only drawback to raising Monarch caterpillars is the need to find their host plant, milkweed. Milkweed is a very common garden plant as well as a common weed. Many nurseries sell several beautiful varieties of milkweed.
If you are lucky enough to find an adult female Saturnid moth such as a Luna, Cecropia, or Polyphemus Moth, you can often coax her to lay eggs. Most wild-caught females have already mated (unless they have JUST emerged). Because females moths are sometimes less picky than some butterflies when it comes to where they lay their eggs, you can simply place the female in a large paper bag and fold it over to close it tightly. Leave her in there for a few days.
When you open the bag again, you are likely to find eggs laid on the surface of the bag. Remove the eggs from the bag carefully (or tear off the section of bag onto which the eggs were laid) and place them in a small container. Lightly mist the container periodically to elevate the humidity slightly. Keep a close watch on your eggs! Before the eggs hatch, you must determine what host plants they will eat and locate a convenient source of that host plant. The caterpillars will hatch in as few as three days. The caterpillars will need fresh host plant as soon as they hatch. Placing a few leaves into the container (and changing them everyday) will be sufficient for your caterpillars until they start growing and eating more.
Where to keep your caterpillars:
Either an aquarium or one-gallon jar is a suitable cage for your caterpillars. The top of your cage should be fastened securely to the cage and can either be screen or cheesecloth held on by a rubber band. You should provide your caterpillars with some sticks that fit securely into the cage for them to pupate on. Do not use a jar lid with holes punched in it. Not only will this provide inadequate ventilation, but the caterpillars can also be cut open by the sharp edges of the holes.
What to feed your caterpillars:
The most difficult task in raising butterflies and moths is to provide your caterpillars with fresh clippings from the host plant appropriate for the species of caterpillar you are raising. Caterpillars are very picky eaters. Each species will only eat very specific plants. Therefore, in order to take care of a caterpillar, it is important to know what kind of caterpillar it is, and what that kind of food it eats. A good rule of thumb is that a caterpillar is most likely to eat the kind of plant you found it on. However, if you find a caterpillar that is not clearly on a host plant, consult a field guide for caterpillars such as Peterson First Guide to Caterpillars, or Caterpillars of Eastern Forests. If the field guides tell you a particular kind of caterpillar may eat more than one type of leaf, provide a selection of those different kinds of leaves for your caterpillar so you can find out what it likes best. If you are in doubt about what kind of caterpillar you have found, it is best to let it go. Caterpillars will starve to death before they will eat the wrong food.
Once you have found the correct food, remember your caterpillars must always have fresh food! Caterpillars will not eat old or dry leaves. The easiest way to feed your caterpillars is to provide them with a live, potted plant in their cage. However, because many host plants are large bushes or trees, this is not always possible. Therefore, it is best to provide new clippings of host plant everyday, and to preserve the food by keeping it in water. However, caterpillars can (and will) fall into vases and jars of water and die. Therefore, keep the food fresh by placing it in floral tubes. (You can purchase floral tubes from most florists for about ten cents a piece.) If you cut too much food at once, give some of it to your caterpillar and put the rest in a glass of water in refrigerator until you are ready to use it. This will keep the food fresh longer. Some host plants stay fresh for a remarkably long time. Other host plants whither quickly.
Always be sure to carefully inspect your fresh plant cuttings for spiders or insects. It is very disappointing to find that you have inadvertently fed your caterpillars to a very fat and happy spider!
How to water your caterpillars:
Caterpillars receive all the water they need from the plants they eat. It is not necessary to provide them with any additional water source. The cage can be misted periodically if it appears dry, because most caterpillars prefer a somewhat humid environment. Be careful not to mist your caterpillars too much, however, because too much moisture can promote the growth of mold.
How to keep your caterpillar cage clean:
Caterpillars have one job in life: eating. Because of this, they produce copious amounts of waste (known as frass). This frass must be cleaned out of the cage every day in order to prevent mold growth and create a healthy environment for your caterpillars. If you are raising butterflies or moths that you know will pupate above ground, you can simply line the bottom of your cage with paper towels. This will facilitate the necessary daily cleanings. However, if you do not know what kind of caterpillar you have, or if you know that your caterpillar is a species of moth that pupates underground, the bottom of your cage should be lined with about two inches of soil.
Handling your caterpillars:
Caterpillars are very susceptible to a variety of bacterial infections, including bacteria we all carry on our hands without knowing it. Be sure to always wash your hands thoroughly before handling the caterpillars. Caterpillars are relatively fragile creatures. Handle them very gently. They can be killed if they are dropped even a very small distance. When caterpillars walk, they may cling very tightly to the surface they are walking on. Never pull them off of any surface (including your hands), because they will often hold so tightly that you can rip their prolegs off before they will let go. If you are changing their host plant, it is best to put the fresh host plant into the cage, then wait a few hours for the caterpillars to crawl onto the new host plant on their own. Then you can remove the old food. Be sure you know how many caterpillars you have and count them all before you throw out old host plant so you do not accidentally throw away your caterpillars!
Do not pick up caterpillars with branching spines! These spines can deliver a very painful sting.
If your caterpillars seem lethargic or have changed color, do not handle them. They are probably preparing to molt or form their pupa. All insects are very vulnerable as they begin to molt. They may also be sick. If your caterpillars die, remove them from the cage immediately to help prevent infection of the other caterpillars in the cage.
Taking care of pupae (chrysalides or cocoons):
Your pupae do not need food or water. An occasional misting of the container will help keep the environment humid, which is necessary for healthy pupae.
Most butterflies and moths will stay in their pupae throughout the winter. Therefore, if your caterpillars pupate in the fall (or at any time during the winter in the case of purchased caterpillars), there is a good chance that they will remain in their pupae until Spring. Remember that your diapausing pupae are still alive. Keep the cage humid with occasional misting. Be sure your pupae are hanging in a proper location for your moth or butterfly to emerge. A newly emerged butterfly must be able to hang high enough that the tips of its wings will not touch the ground when they are fully expanded. If a new butterfly does not have enough vertical and horizontal space for its wings to expand and dry, its wings will not form correctly and the butterfly will not be able to fly. If the butterfly falls to the ground when it emerges, it will not be able to expand its wings, and it will die. (If your pupae are from a moth species that pupates underground, they does not need to hang. Just be sure there are plenty of sticks so that a newly emerged moth can climb up on to hang.)
If your caterpillars did not pupate in a location with enough space to emerge, you must move the pupae to a better location. If the pupa is on a stick, carefully move the stick to a higher location with more space. If the chrysalis has fallen off of a stick, you can hang it by placing a dot of hot glue on a piece of paper and then place the tip of the chrysalis in the slightly cooled (but still liquid) hot glue. Hold the pupa on the paper a few seconds to allow the glue to harden. Now the pupa can be hung by pinning through the paper onto a piece of cardboard or cork.
Most butterfly pupae (chrysalides) will either turn dark or become clear when the butterfly is ready to emerge. When this happens, be especially sure that your cage is humid. Keep a careful watch! It only takes a few seconds for a butterfly to come out of its pupa!
Dead pupae often turn very dark. If you gently bend the abdominal region of the pupa and it stays bent, the pupa is probably dead.
When your butterflies emerge:
Be sure to provide sticks that hit the bottom of the cage so a fallen butterfly or moth can climb up the sticks to find a place to hang. If you would like to keep your butterfly for a few days to observe it, you can build a butterfly house. Be sure to release it within a few days!
If you have a large Saturnid moth such as a Luna Moth, Cecropia Moth, or Polyphemus Moth, these moths do not have a digestive system as adults! You do not need to worry about feeding them. Their adult life span is no more than four to five days.
