The caterpillar is only one of four stages in the life cycle of a butterfly. This article will introduce you to the caterpillar life cycle stage and a few interesting facts about caterpillars. But first, let’s look at the entire life cycle of a butterfly to put things in perspective.
Butterfly Life Cycle – Egg: Adult butterflies lay their eggs on the leaves of their host plant. Each butterfly species has certain plants that their caterpillars must eat to live and grow. Some butterfly species are very specific to one or two plants while others may be able to eat a family of plants. Butterfly eggs are small in general (like the size of a pin head) and usually hatch in about 3-7 days.
Butterfly Life Cycle – Caterpillar: The caterpillar hatches from the egg and usually the first thing it does is eat the egg shell. After that it will start consuming the host plant. The caterpillar will spend the next several weeks eating and growing since that is its main purpose.
Butterfly Life Cycle – Chrysalis: This stage is often a called a cocoon, but generally a cocoon is the pupa stage of a moth while a chrysalis is the pupa stage of a butterfly. At this point the caterpillar has made its final molt into a pupa and in about 1-2 weeks an adult butterfly will emerge.
Butterfly Life Cycle – Adult Butterfly: The adult butterfly will spend its time eating nectar and mating/laying eggs. Many butterflies only live about 2 weeks, however, some species such as the monarchs will overwinter by migrating south and thus will live for many months.
Caterpillars are truly eating machines. Before they become a chrysalis their body mass will increase thousands of times. With all this rapid growing they end up molting several times before their final molt into a chrysalis. They grow their new exoskeleton beneath their current skin then when the time comes they split the old skin off. Many times they will eat the old skin before returning to their leaf-munching.
Caterpillars will change their appearance sometimes dramatically between their molts. An example is the black swallowtail caterpillar. When it is very young it is black with a white saddle. By the time it becomes ready to pupate it has become a beautiful mix of stripes and dots with colors of yellow, white, black and green. That can make identification more difficult since their appearance depends on their age.
Caterpillar identification is not really that difficult if you happen to know what plant they are eating. If you can identify the plant then it becomes much easier to identify the caterpillar since they are so particular to their own host plant. Just Google the “plant name” plus “caterpillar” or “host plant” and you are very likely to find the butterfly or moth species to which the caterpillar belongs.