The Suppressor Beetles are robotic implants designed by the Yashida Corporation to slow down genetic anomalies within cells of the host body they were placed in.
The suppressor beetles are capable of secreting an immuno-anesthetic solution into the host body, which prevents the host from feeling pain or discomfort. The specific purpose of the beetles are to suppress certain cells that its limited AI detects as being potentially harmful to the host, ranging from mutated cancer/tumor cells to mutant abilities, like Logan's regenerative healing factor.
The suppressor beetles are first seen in Ichirō Yashida's personalized chamber, swimming around in two clear blue vials. Logan looks to the MRI scan of Yashida's chest and sees several suppressor beetles attached to his lungs, to slow down the rate of his cancerous tumors.
When Logan is sleeping he sees a vision of Jean Grey and begins kissing her, before he realizes that it is Viper, Yashida's oncologist, who plants two suppressor beetles inside him, to slow his healing. At Yashida's funeral the following day, Logan is shot by several Yakuza thugs, and finds his wounds are not healing. He suspects that Viper put something inside of him, a suspicion that is confirmed once he puts himself in Yashida's chair and scans his chest.
Logan attempts to cut out the two suppressant beetles with his claws, temporarily dying on the operating table. He revives himself moments later, crushing the beetles in his hand.