|By watching butterflies grow from eggs or caterpillars to the adult stage, we can observe their complete life cycles.
To obtain eggs of non-threatened species, look for female butterflies laying eggs or check the species' host plants at appropriate times. Place the host plants with eggs attached in a small jar or vial until the eggs hatch. Caterpillars can be reared easily in wide-mouthed jars, plastic boxes, or transparent plastic bags. But never place caterpillars in a tightly closed container without first providing for air circulation. For jars with metal lids, punch holes in the lid that are smaller in diameter than the caterpillars, or cover a wide-mouthed jar with a piece of nylon stocking. Also prevent very dry or wet conditions.
Different types of caterpillars should be kept in separate containers. Crowding too many caterpillars into a single container is asking for trouble; they may devour each other, or disease may lead to mass mortality. Put sticks or other supports inside for attachment of chrysalises. Over-wintering chrysalises of some butterflies, such as swallowtails, may be kept outdoors or refrigerated until spring.