Kochū

The are a species of insect used by members of the Aburame clan, seen in Book of Dark Night. They can produce a poison that will paralyse their victims and kill them a short while later; the poison disappears upon death, preventing it from being found during autopsies. Danzō Shimura notes kochū are perfect for performing assassinations, as they are as imperceptible as mosquitoes yet as deadly as scorpions. Yōji Aburame is the only clansman known to use kochū. Because he cannot talk, Yōji controls the kochū in such a way that their sounds resemble speech, an effective yet exhausting accomplishment.

Trivia

 * Their name comes from kodoku, a type of poisonous magic in Japanese folklore.