|Manga Debut||After that Suspect!|
A Bug (蟲, Mushi) is an organism that originate from Adolla that has a spark of the Adolla Burst inside them. When exposed to humans, it forces Spontaneous Human Combustion in them by merging the person with their Doppelgänger, which commonly turns them into Infernals, but if compatible, they can become a Third Generation or presumably a Second Generation.
Rekka Hoshimiya stored his bugs in glass vials, removing the lid and pressing the vial into the person he wishes it to sting. This also allowed him to detect the Adolla Burst inside Shinra Kusakabe by observing how the insect reacted to his presences. Rekka also used the Bug on Nataku Son, turning him into a Third Generation, and eventually awakening the Adolla Burst, and becoming the Sixth Pillar.
Haran ingested a Bug during the battle with Asakusa, transforming himself into a Demon Infernal. Another member of the order allowed a Bug to turn him into an Infernal as a means of escaping interrogation.