What is the name of the forked, fleshy organ used by swallowtail larvae for chemical defense?

Answer

Osmeterium

The osmeterium is a specialized, repugnatorial organ that larvae turn outward to release an unpleasant odor when they feel threatened.

What is the name of the forked, fleshy organ used by swallowtail larvae for chemical defense?
insectbutterflyFeaturewingSwallowtail