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Identifying Larvae

Monarch caterpillars and queen caterpillars are close relatives and look very similar. They both only use milkweeds as their host plant. In addition, the caterpillar of the black swallowtail butterfly looks a lot like a monarch. Here are some ways you can identify each one.
Note: A caterpillar is called a larva. Caterpillars are called larvae.

Monarch
Danaus plexippus

Monarch: Two pair of filaments, one on each end.

Yellow, black and white stripes.

Queen
Danaus gilippus

Queen: Three pair of filaments one on each end and one in the middle.

Filaments are reddish and black stripe surrounds yellow dot.

Black Swallowtail
Papilio polyxenes

Black swallowtail: Larva is often mistaken as a monarch. If you see a caterpillar in dill, rue, fennel or parsley, you likely have a black swallowtail larva.

Black swallowtail: Photo by Laura Miller

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