A defensive secretion becomes a coating
A millipede’s chemical defense is meant to make an attacker back off. When a lemur bites or handles one, the millipede releases a pungent secretion from its body. The lemur then works that fluid through its fur, turning the insect’s defense into a kind of external treatment.
The proposed benefit is practical: the secretion may discourage parasites that would otherwise settle on the lemur’s skin or coat. It is not a carefully measured dose, though. The same chemicals that make the millipede unappealing can affect the lemur, too.
Grooming turns treatment into a temptation
After anointing itself, a lemur may groom, licking its fur and taking in some of the secretion. That can produce signs of intoxication. So the behavior has an awkward built-in tradeoff: the lemur spreads a potentially useful substance over its body, then risks swallowing it while cleaning up.
The sequence matters. The millipede does not simply serve as food, and the lemur is not just rubbing against a harmless object. Its defensive response supplies the substance; the lemur’s handling spreads it; and later grooming can carry it from fur into the mouth. A possible parasite deterrent and an intoxicating exposure come from the same chemical defense.
