1. retractable, forked, scent-producing organs found behind the head of caterpillars in the swallowtail butterfly family, used for defense against predators
Usage: entomology; plural form

Examples

• When threatened, the swallowtail caterpillar extends its bright orange osmeteria.
• The osmeteria release a strong, unpleasant odor to deter predators.
• Scientists study the chemical compounds produced by caterpillar osmeteria.
• The osmeteria appear as two horn-like projections when fully extended.
• Black swallowtail larvae use their osmeteria as their primary defense mechanism.
• The osmeteria quickly retract when the threat passes.