from The American Heritage® Dictionary of the English Language, 4th Edition
- n. An eversible glandular sac on the first thoracic segment of many caterpillars that secretes an unpleasant-smelling substance to ward off predators.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. One of a pair of scent organs in the larvae of certain swallowtail butterflies.
from The Century Dictionary and Cyclopedia
- n. In entomology, any organ devoted to the production of a scent or odor; specifically, a forked process found on the first segment behind the head of certain butterfly-larvæ.
Not only do the earliest books that I can find spell it "osmeterium", but the Greek root is "osme".}
The Black Swallowtail Caterpillar has an orange “forked gland”, called the osmeterium.
As with other swallowtails, these caterpillars 'posses a bright reddish orange, y-shaped gland called an osmeterium, which contains a mixture of highly noxious chemicals that smell like rancid butter.
I didn’t know about the osmeterium — kinda freaky!
When in danger the osmeterium, which looks like a snake’s tongue, everts and releases a foul smell to repel predators.