Monarch Caterpillars

This monarch caterpillar is crawling on a milkweed leaf. Why do you think it has two sets of antennae?

Finding a monarch caterpillar is easy--if you know where to look. Monarch caterpillars only eat milkweed. Not many people grow milkweed in their gardens, but you can find it on the edges of fields and meadows. If you find the milkweed, you can find a caterpillar.

Milkweed has big, sturdy leaves. Look for places where the leaves have been bitten. This is a good clue that monarch caterpillars might be nearby! The caterpillars crawl slowly and spend most of their time on just one milkweed plant. They don't have to run or hide. Nothing eats them. The milkweed that they eat makes them poisonous.

In September, the monarch caterpillars here in Pennsylvania are eating and eating and eating. The caterpillar in the picture formed a chrysalis the day after the picture was taken. Once it emerges from the chrysalis, the butterfly will join other monarchs on a flight to a warmer places for the winter.