A female Monarch butterfly can lay hundreds of eggs over her lifetime.
On average, a female will lay between 300 to 500 eggs, although this can vary based on environmental conditions, availability of milkweed (their host plant), and other factors.
She typically lays them one at a time on the underside of Milkweed leaves, which is the primary food source for Monarch caterpillars. Without Milkweed you will not have Monarch Butterflies.
Milkweed Seeds
Seeds for growing plants in the Milkweed genus (Asclepias); required for all Milkweed butterflies, like the Monarch and Queen.