Butterflies are beautiful insects in the order Lepidoptera, a huge order which contains thousands of species. They have captured the human imagination for thousands of years, featuring prominently in our mythology and art.
Butterflies have a fascinating life cycle and the adults are perhaps the most showy and entertaining of all insects, displaying interesting behaviors and amazing colors.
They can be challenging to rear in captivity, however, and do not live long, but if you follow a few simple rules it is entirely possible to raise many generations of butterflies from the comfort of your own home.
Setting up a Butterfly Enclosure
The first step in keeping pet butterflies is to set up a suitable enclosure.
Keep your butterflies in an enclosure with bright light, away from extreme fluctuations in temperature. Adult butterflies appreciate having access to direct sunlight, but should always be able to escape to a shadier spot to avoid overheating. Caterpillars should be exposed to day/night cycles of light to develop properly, so keep them in indirect bright light near a window.
- Netcages: For raising small numbers of butterflies it is hard to beat the netcage. Netcages are cheap, portable, and provide excellent ventilation. They can also be large, allowing adult butterflies to live within them for a time.
- Terrariums: when rearing caterpillars it is possible to use glass or acrylic tanks. Though too small for butterflies to comfortably live in, terrariums will prevent desiccation of caterpillars and can be heated to provide a warm and humid home for tropical species. Tanks can become stuffy, however, and encourage mold growth if you are not careful.
- Greenhouses: Zoos and museums often keep butterflies in greenhouses. Greenhouses provide warmth and lots of flight room for butterflies. Host plants can be grown inside the greenhouse, allowing for many generations of butterflies to be raised for far less work.
- Butterfly Room: If you don’t have a greenhouse, butterflies can be raised in a room dedicated to them. This will give the adults enough room to fly and mate, and caterpillars can be raised on host plants kept inside the room. You can grow the plants with grow lighting or sunlight from a window.
- Free-range: the relationship between butterflies and their host plants is often so close that larvae will not leave their host plant for any reason. As such it is sometimes possible to rear caterpillars on host plants kept indoors, with no enclosure around them.
- Outdoors: perhaps the best way to rear your own butterflies is to plant flowers and host plants for native butterflies in your garden. That way you can simply enjoy the beautiful butterflies that are attracted to the flowers and provide them a place to lay their eggs with the host plants.
There are a variety of substrates you can use to keep your butterflies happy and healthy. A good substrate will absorb moisture while also maintaining humidity. Choose your substrate based on the needs of the species you are raising.
- Paper towels: these absorb moisture well and become dirty quickly. You will need to change these regularly.
- Gravel: lasts a long time, maintains humidity, and does not mold. Becomes dirty and must be washed, however. Very small caterpillars can become lost inside, though.
- Sand: absorbs moisture and maintains humidity. Caterpillars will not be able to drown, either. Can be kept damp or dry to suit different species.
- Coconut coir: absorbs moisture and waste while also balancing the humidity.
- Soil: Very similar to coir, but you will need to sterilize it to avoid pathogens and it must not contain any fertilizer or insecticide.
If you are raising caterpillars native to your region, room temperature will be enough for the health of your pets. Tropical butterflies will need supplemental heating to develop properly, which in the case of tropical butterfly houses is usually a part of the heating of the greenhouse they live in. Heat lamps and pads can provide heat for tropical butterfly caterpillars, while a larger gas or electric heater might be needed to keep the larger spaces needed by the adults warm.
Humidity and Ventilation
Caterpillars obtain most the water they need from the leaves they eat, and for caterpillars from dry areas this is all the water they need. It is a good idea to mist your tropical caterpillars daily, however, to simulate dew, which will help keep the enclosure humid enough and provide supplemental water for the caterpillars. If you are keeping adult butterflies it is very important to offer a water source, though you must be careful if you are keeping caterpillars and adults in the same enclosure. A shallow pan of water filled with pebbles will work nicely, preventing caterpillars from drowning while giving the adults drinking water.
In natural settings caterpillars and butterflies would be living in the open air. As such, they need excellent ventilation to avoid succumbing to fungal and bacterial diseases. The enclosure you keep them in needs to have at least one side that is mesh or netting.
This section covers diet & feeding needs of both caterpillars and butterflies.
Food for Caterpillars
Almost without exception, caterpillars are herbivorous and require large amounts of plant matter to feed on. The amount of food that a caterpillar can eat is often incredibly starting – you may find yourself replacing the food ever couple of days, particularly if you are keeping multiple caterpillars. You will need a constant supply of the host plant to feed your caterpillars. In order to do this you can grow the plant yourself, ensuring that you always have some on hand, or you can find a place where you can harvest branches from the host plant. You can keep caterpillars on living plants, or you can offer them branches kept in a vase full of water. If you choose to go this route it is important to either fill the vase with gravel or cover the opening with netting to prevent drowning.
Each species of butterfly only has a certain range of hosts upon which they can feed. Some butterflies can only feed on a single species of host, while others can feed on a wide range of plants. These are some of the most popular species of butterflies to keep with the host plants they are able to feed on:
- Monarch: milkweed
- Painted Lady: mallow, hollyhock, thistle
- Cabbage White: brassicas
- Zebra Longwing: passionflower
- Black Swallowtail: dill, carrot, fennel, Queen Anne’s Lace
Food for Butterflies
Adult butterflies feed on nectar, dung, and even sweat. They will do fine consuming a solution of sugar water, similar to what you would fill a hummingbird feeder with, supplemented with fruit juice. You can provide this in a colorful dish or bottle cap, preferably a solid shade of yellow, blue, or red. There are also special butterfly feeders available that you can fill with the sugar solution, and some butterfly species will feed from hummingbird feeders. It is important to note, however, that some butterfly species do not feed at all as adults so it is important to do your research.
Wondering if you can keep other species / pets with your butterflies? This section is for you!
Butterflies and their larvae, as a generalization, do not cannibalize each other. Butterfly species of the same species can be kept together, provided there is enough food and the enclosure is large enough to prevent the spread of disease.
Butterflies of different species can also be reared and kept together successfully, with a few caveats. The first thing to note is that you need to ensure both species have adequate amounts of food. If both species feed on the same host they can compete for food, so it is a good idea to increase the size of the enclosure and provide extra host plants. Adults can be territorial, often making quite an entertaining display of flying at each other and even their keepers, but usually don’t harm each other.
If the substrate of your butterfly enclosure is something like gravel, coconut coir, or soil you might want to consider adding cleaner organisms to the enclosure. Isopods, small cockroaches, millipedes, and springtails will not harm your caterpillars or butterflies but will help consume insect frass and mold.
Butterflies are generally peaceful and harmless creatures and can be kept with similarly pacifistic animals. Many museums make beautiful displays in which butterflies are kept in greenhouses that contain fish ponds or herbivorous reptiles like tortoises. Butterflies are also quite compatible with stick insects, provided the butterflies and stick insects feed on different host plants. It should go without saying that butterflies should not be kept with predatory animals like birds or mantises.
As caterpillars develop they put on weight extremely quickly, doubling in size in a matter of weeks. In order to do so they consume massive amounts of plant material. This means that they poop, often and in great quantities. This poop, known as frass, can promote mold and bacteria growth and cause health issues for your caterpillars. You should either keep janitor organisms in the enclosure with your caterpillars, which will feed on frass and mold, or remove frass from the tank as often as possible.
Caterpillars are surprisingly sturdy creatures that can deal with some handling. Handling your caterpillars should still be avoided, however, as it causes stress. Most injuries happen during handling as well, as it is very easy to drop or crush caterpillars by accident. In addition to this many caterpillars are very well-defended with stinging hairs that can be extremely irritating to skin and mucous membranes.
Adult butterflies should not be handled. Their wings are exceptionally fragile and break very easily. They are also covered in fine scales that easily come off, particularly when they come into contact with the oil on our skin. Losing these scales not only decreases the beauty of the butterfly but can sometimes make it harder for the butterfly to fly.
Butterfly Health & Disease
This section covers some thing that you should look out for regarding butterfly heath & common issues.
Molting is a very dangerous time for all arthropods and butterflies are no exception. Adults do not molt but the caterpillars molt several times before pupation. Molting can go wrong, particularly if the humidity is too low, and the caterpillar can have trouble escaping it’s own shed exoskeleton. This is often fatal which is why it is so important to mist your caterpillar enclosure regularly and keep the substrate moist. If a caterpillar does not molt properly you can help remove bits of shed exoskeleton with forceps.
Injuries can happen when opening and closing the enclosure as well as when handling your butterflies. Minor injuries to caterpillars will likely resolve within a molt, but most injuries that compromise the exoskeleton will ultimately be fatal to the caterpillar. Adult butterflies will often damage their wings, which can actually be repaired by replacing the damaged part of the wing with a piece of wing from a dead butterfly. Contact cement will hold the wing together and allow the butterfly to fly once more.
Because caterpillars consume large amounts of herbaceous matter they are at increased risk of insecticide poisoning. Be extremely careful as to where you find your butterfly food, as many plants in urban and suburban environments are sprayed. Plants in agricultural land may be sprayed with pesticides and herbicides, both of which can be lethal to your butterflies. Make sure your caterpillar food has not been treated with any kind of pesticide, and if you cannot be sure you will need to grow the plants yourself.
Fungus & Bacteria
Fungal diseases can quickly kill a caterpillar. To minimize the risk of fungal infection maintain proper ventilation and clean up waste before mold can set in. Bacterial infections are thankfully quite rare and can be prevented in very similar ways to fungus.
Many butterflies are attacked by a variety of parasites and parasitoids. Parasitoids are wasps and flies that complete their life cycle by essentially ‘infecting’ their host, feeding on it and causing its death. Parasitoids live naturally in the environment and can be attracted to your butterflies, infecting either the eggs or the caterpillars. The only way to prevent parasitoids from killing your pets is to keep them in an enclosure that parasitoids cannot access.
The lifespan of butterflies varies greatly depending on the species. Most adult butterflies live no more than a month or so, though some of the larger species can live up to nine. The monarch is a good example, as it will migrate south after pupating before returning north to lay eggs.
This section covers the details of breeding and raising butterflies.
Butterflies will generally only mate in large enough spaces. They will often chase each other or congregate in one specific part of the enclosure. There is little chance your butterflies will mate unless you provide them with a very large space (at least several feet tall and wide) that preferably contains host plants and sunlight.
In order to lay eggs you will need to present your butterflies with host plants of the correct species. If they have mated they will lay eggs on the host plant without any prompting. Butterfly eggs are often quite small and can be hard to see without a hand lens, so you may need to spend some time searching before you will find any eggs.
Caring for the Young
When butterfly larvae first hatch they are extremely tiny, so do not disturb them until they are able to grow a bit. Make sure they have constant access to the host plant and if any leave the host plant or fall off, use a paintbrush to gently move them back. For tropical species, be sure to maintain the humidity by misting.
One of the most exciting events when rearing a butterfly is pupation. The caterpillar will look for a stable place, hang upside-down, and sheds its skin to reveal a chrysalis. It is within the confines of this chrysalis that the transformation from caterpillar to butterfly takes place. When your caterpillar starts to pupate you do not need to do very much. Simply keep the chrysalis out of direct sunlight, maintain the proper humidity and heat, and just wait. After a period of time (depending entirely on the species of butterfly) the fully-grown butterfly will emerge. The wings will appear crumpled and limp, which is normal. It is important not to touch the newly-emerged butterfly, which will slowly pump expand its wings by pumping fluid into them.
In United States it is illegal to ship butterflies, butterfly pupae, or caterpillars across state lines without a permit. The permits are fairly easy to apply for, but these permits are fairly restrictive and you are generally only allowed to purchase species native to your region. There are no limits on purchasing butterflies within a state and it is legal to raise any butterfly native to or naturalized in your state provided it is not endangered.
This means you will either have to purchase butterflies within your state, which may not be possible, or find them in the wild. You should not take butterflies from natural areas, however. Not only is it important to conserve our biodiversity but butterflies are often protected, so it is illegal in most places to collect native species from the wild unless they are on your own property. A good way to procure butterfly larvae is to plant a host plant and wait for a butterfly to deposit eggs. You can then rear the eggs and larvae yourself.
If you do raise butterflies not native to your region, it is also important to note that you should never release these butterflies into the environment. Butterflies, though beautiful, can become invasive and cause damage to agricultural and natural resources. If you must get rid of non-native butterflies, either find them a new home or euthanize them.