Here are some photos of Milkweeds in my garden. Female Monarchs typically lay eggs on the underside of the leaves. When the caterpillar emerges it eats the egg, then begins to feast on the tender Milkweed leaves. Tiny caterpillars are often found on the underside of the leaves, as the caterpillar gets larger it may be found anywhere in the garden, however the caterpillar ONLY feeds on Milkweed. (there are several varieties of Milkweed depending on location) These are most common Milkweeds in northern US.