From Halopedia, the Halo wiki
Intelligence data gathered by multiple spy gnats may be collected at a central transmitter to then be relayed elsewhere. Microbursts of data from gnats can be sent at random intervals. Gnats are unable to transmit information from realspace to a receiver in slipspace.
History of use
In December of 2553, the Spartan-III super-soldier Ash-G099 used spy gnats to bug the Mudoat starsloop, Stolen Faith. He and the rest of his Ferret were undercover aboard the Kig-Yar-crewed vessel as part of Operation: RETRIBUTION at the time. The gnats he placed relayed audio data to the Sahara-class heavy prowler UNSC Silent Joe, where it was downloaded by signals intelligence personnel.
List of appearances