A monarch butterfly is here pictured with an aster plant.
The monarch butterfly and the milkweed plant are interdependent.
The larvae of the monarch butterfly feed on milkweed leaves. These leaves are poisonous to most insects. As the butterfly eats more and more milkweed, the poison builds up in its body. That makes the butterfly poisonous to the birds! That's how the monarch butterfly protects itself from being eaten!