As a part of the A-Z Photographic Glossary of Biological Terms challenge, today it is R for Repugnatorial gland as illustrated by this Desert Stink Beetle (Eleodes sp.; Tenebrionidae), from the Franklin Mountains State Park in El Paso, Texas.
Repugnatorial glands are also described as “stink glands” or “odoriferous glands” or more properly “ozadenes,” from which an arthropod (primarily insects and myriapods) can emit a foul-smelling and often toxic secretion or vapor, used in defensive situations to repel predators.
In this example, the Desert Stink Beetle will often stand on its head to allow for a more effective spraying of its noxious secretion however certain of their predators, like Grasshopper mice who are already adept at disabling venomous scorpions and centipedes, get around this problem by grabbing the beetle, jamming its behind into the sand, and then eating it head first, similar to this mouse’s strategy when dealing with a scorpion.
Now based in Belize, there are a number of arthropods here that utilize repugnatorial glands including many species in the Pentatomidae family of stink bugs like this one (probably Peromatus sp.) found in Unitedville, Cayo District
and this polydesmidan (“flat-backed”) millipede found in Alta Vista, Stann Creek District, which secretes hydrogen cyanide gas to both deter predators (including humans!) and knock their prey dead!