It is an important recycler of nutrients in rainforests, and favours plant health. Many insect species, usually in their larval stages, accumulate their frass and cover themselves with it either to disguise their presence, or as a repugnatorial covering.
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Bedstraw hawk-moth caterpillar leaving the frass behind Typical sculpting of a frass pellet of a large caterpillar A thistle tortoise beetle larva carrying a mass of its own frass as a repugnatorial defence. Frass refers loosely to the more or less solid excreta of insects, and to certain other related matter.
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Swallowtail butterfly Swallowtail butterflies are large, colorful butterflies in the family Papilionidae, and include over 550 species. Though the majority are tropical, members of the family inhabit every continent except Antarctica. The family includes the largest butterflies in the world, the birdwing butterflies of the genus Ornithoptera. Swallowtails have a number of distinctive features; for example, the papilionid caterpillar bears a repugnatorial organ called the osmeterium on its prothorax.
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Aposematism is the warning coloration to signal potential predators to stay away. In many chromodrorid nudibranchs, they take in distasteful and toxic chemicals emitted from sponges and store them in their repugnatorial glands (located around the mantle edge). Predators of nudibranchs have learned to avoid these certain nudibranchs based on their bright color patterns. Preys also protect themselves by their toxic compounds ranging from a variety of organic and inorganic compounds.
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There have been very few observations of predation on M. leonina; the few known observations of predation have mostly involved the crab Pugettia producta. The main defense against predation is thought to be its ability to produce an odorous secretion that is repellent to other organisms. The gland that produces these secretions are known as repugnatorial glands. Some sources have described the secretion as a watermelon-like smell.
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The Coreidae commonly are oval-shaped, with antennae composed of four segments, numerous veins in the membrane of the fore wings, and externally visible repugnatorial stink glands. They vary in size from 7 to 45 mm long, which implies that the family includes some of the biggest species of Heteroptera. The body shape is quite variable; some species are broadly oval, others are elongated with parallel sides, and a few are slender. Many species with the "leaf-footed" tibiae are very slender with conspicuous expansions of the hind tibiae, but some robust species also have decided expansions.
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Some species are covered with spines and tubercles. As an example of these, the tribe Phyllomorphini Mulsant & Rey, 1870, are strikingly aberrant, with thin legs, spiny bristles, and laciniate outlines and adornments. Many of the more robust species have grossly enlarged, thickened, and bowed hind femora armed with spikes on the inner edge, and with hind tibiae to match, though the enlargement of the tibiae is less exaggerated. In the nymphs, the openings of the two repugnatorial stink glands of the Coreidae are visible as two projections or spots on the medial line of the dorsal surface of the abdomen, one at the anterior and one at the posterior edge of the fifth abdominal tergite above the glands inside.
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Ammodesmus nimba from Guinea, West Africa, curled in a defensive coil Due to their lack of speed and their inability to bite or sting, millipedes' primary defence mechanism is to curl into a tight coil – protecting their delicate legs inside an armoured exoskeleton. Many species also emit various foul-smelling liquid secretions through microscopic holes called ozopores (the openings of "odoriferous" or "repugnatorial glands"), along the sides of their bodies as a secondary defence. Among the many irritant and toxic chemicals found in these secretions are alkaloids, benzoquinones, phenols, terpenoids, and hydrogen cyanide. Some of these substances are caustic and can burn the exoskeleton of ants and other insect predators, and the skin and eyes of larger predators.
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