The eggs laid in my earlier post (“Laying Eggs”) hatched after all. I’ve been watching this process for several years now acquiring knowledge as I go and one thing I’ve learned is time varies depending on the weather. I’m also just learning to identify the early stages of the process, namely the egg and the first instar, both of which are really tiny and on the underside of the Milkweed leaf. Rearing Monarchs in the wild, as opposed to containers, involves alot of crouching down and looking under leaves. So the tiny phases are easy to miss.
An “instar” is a phase between two molting periods in the development of an insect larva. The Monarch caterpillar goes through 5 instars in about 10-14 days. In the first instar the caterpillar is only about 1/8″, which is about the size of an ant. So it’s no wonder I missed this phase. And at the end of the 5th instar it’s about 3″ long.
The caterpillar in the photo above is about 1/2″, which is either the 2nd or 3rd instar. Here are examples of other sizes.
When a caterpillar is ready to molt it rests and rests, to the point you think it’s dead because it hasn’t moved in forever. But then it finally molts, which except for the final molt, looks something like crawling out of a skin-tight sleeping bag. In some cases the caterpillar eats the old skin. Yuck!
Caterpillars really become chow hounds in the 4th instar where they usually eat an entire Milkweed leaf in under an hour. Remember, a Monarch lays one egg per leaf. So this is when you have to ask yourself, do I have enough Milkweed?
A fifth instar Monarch hangs upside down in a “J” position, spins a silk button to hang from, rests for about 10-12 hours and then sheds its skin for the last time. A chrysalis it becomes.
It’s not uncommon for me to have 12-20 caterpillars in my atrium at one time. Today I have caterpillars from two female butterflies. Some are in their 4th or 5th instar while others are just starting out.
Caterpillar, caterpillar, crawl, crawl, crawl;
Don’t fall off the garden wall.
Caterpillar, caterpillar, eat, eat, eat;
Grow so fat on your furry feet.
Caterpillar, caterpillar, rest, rest, rest;
Soon you’ll change to be the best.
Caterpillar, caterpillar, try, try, try;
One day you’ll be the best butterfly
— C Richard Miles
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