Butterfly Life Cycle: Caterpillars

## **Learn about caterpillars and how to provide for them.**

by Jill Staake on May 13, 2017.

Experienced butterfly gardeners know their gardens need both nectar plants, for adult butterflies, and host plants, for caterpillars to eat.

The best butterfly gardens provide places for every part of the butterfly life cycle, from egg to caterpillar, chrysalis to adults.

This series of posts explores each of these butterfly life cycle steps, and how your own garden can better support butterflies during those steps.

From the moment a caterpillar crawls from its tiny egg, it has only one thing on its mind: eating.

While a *newly-hatched* caterpillar is barely the size of a pinhead, it will grow to as much as 100 times that size in just a few weeks.

It eats its first meal almost immediately upon hatching – its own eggshell.

This provides valuable nutrients to give the caterpillar, also known as a larva, a good start.

This little insect’s feast days have just begun, though.

Next the caterpillar moves on to its host plant, which varies and is specific to each species.

The egg was laid on or nearby the plant, often on the freshest new growth, so the buffet is right nearby.

The caterpillar may be solitary at this point, or could be joined by several dozen of its brothers and sisters.

This behavior, known as gregarious feeding, provides more protection for each individual caterpillar in the same way a school of fish does in the ocean.

Alone or in a group, though, the caterpillar feeds more or less constantly during daylight hours.

At night, it usually finds a hiding place, often in the soil at the base of the plant.

   With all this eating, a caterpillar grows exponentially.

In a few days, in fact, it outgrows its skin.

A caterpillar is an insect, after all, and that means it has an exoskeleton.

It’s not hard, like that of a beetle.

Caterpillar exoskeletons are slightly stretchy, to allow for growth.

But as they grow, they eventually reach the limits of their skin.

They still have a lot of growing to do, so they have to choice: it’s time to molt (*also spelled “moult”*).

   Molting is basically the shedding of the skin, like a snake.

They wiggle out and crawl away from it (*some species actually turn around and it eat*).

Now they can start to eat their host plant again.

They repeat this process several times during this part of the butterfly life cycle.

The period between each molt is known to lepidopterists as an “*instar,*” and most butterfly caterpillars have about five of them.

They can look the same but bigger in each instar, or they can look strikingly different.

Generally, it takes them about two weeks to reach full size.

    A caterpillar’s body is basically one long digestive tube.

Food goes in the mouth, the digestive system removes all the nutrients, and solid waste comes out the back.

This waste is known as “*frass*,” and there can be a shocking amount of it as the caterpillar grows.

Sometimes you can even locate caterpillars in your garden just by looking for the frass they’ve left behind.

A caterpillar is a tasty meal for a huge variety of predators, including birds, ants, and wasps.

They’ve developed a variety of defenses in response.

Some caterpillars hide by rolling their leaves around them while they feed, using thin strands of silk.

Others have amazing camouflage, looking just like the leaves nearby or the branch of a bush.

Others don’t try to hide; instead, they absorb toxins from their host plants to make themselves poisonous, or at least *bad-tasting.*

They advertise this by bright colors.

Many caterpillars have spikes on their bodies (*known as tubercles*) that make them unpleasant to swallow.

And it should be noted that some of those spines are actually venomous and can cause nasty reactions in humans.

Good rule of thumb with nature:

It you don’t know what it is, don’t touch it.

    Even with a variety of defenses, many caterpillars don’t make it to the end of this part of the butterfly life cycle.

An average female butterfly can lay 300 – 1000 eggs; if they all became butterflies, the world would actually be a pretty scary place.

Many eggs are eaten before they hatch, and many more become someone’s dinner as caterpillars.

They can also succumb to disease, bad weather, and – increasingly – pesticides.

Butterfly gardeners should avoid use of any type of pesticides in their gardens whenever possible.

Of those 500 or so eggs, perhaps 25 will live to be full-size caterpillars.

For those that do, the most magical and mysterious part of the butterfly life cycle is about to begin – metamorphosis.