
Milkweed Leaf - Asclepias syriaca
If you spot a U-shaped hole in a milkweed leaf, turn it over and you may find a monarch caterpillar.
A monarch caterpillar's first meal is its egg shell. Next, it eats milkweed leaf hairs, and then finally, the leaf itself. The first holes it chews are broadly U-shaped. The shape of the hole is important because it prevents the sticky sap from flooding the leaf and gluing the caterpillar's mandibles (mouthparts) together.
Habitat: Milkweed
On the underside of the leaf:
"Asclepias syriaca" is a species of flowering plant. It is in the genus "Asclepias", the milkweeds. This species is native to southern Canada and of much of the conterminous eastern U.S., east of the Rocky Mountains, excluding the drier parts of the prairies.