How to Identify Swallowtail Caterpillars

Swallowtails are a diverse subgroup of insects in the Papilionidae family. There are 28 species of swallowtail butterflies that are native to North America, although the Papilionidae family is much larger, totaling 551 species in all. Some species are listed as endangered or threatened, for example, Schaus swallowtail, Luzon peacock swallowtail and Homerus swallowtail. Identifying members of the swallowtail family is not difficult since they all share similar morphology in the caterpillar state: tucked head, large abdominal segments near the front, smooth bodies and osmeteria.

Things You'll Need

• Magnifying glass

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Instructions

1. • 1

     Examine the angle of the head: swallowtails have downward-facing heads.

   • 2

     Note the widest or broadest section of the caterpillar's body; swallowtails have broad segments at the front of their abdomen, behind their head between their front legs and rear prolegs.

   • 3

     Touch the caterpillars skin if you are sure the caterpillar is not poisonous; the skin should feel smooth.

   • 4

     Look for osmeteria at the top of the caterpillar's head; osmeteria are brightly colored protrusions that emit a sweet and pungent aroma. Bear in mind the osmeteria will only be visible if the caterpillar is alarmed, as they are a defense mechanism.