The Laka was a bug found on the planet Arnessk. Its intestine contains a substance that acts as a powerful mind-deadening drug; according to Utu-Noranti Pralatong, just "...stick it up your nose! You'll get a jolt – wham! And for five hundred microts nothing bothers you."
Noranti later provides Crichton with "distillate of laka", made from the same substance produced by the bug, so he can forget the pain caused to him by the presence of Aeryn.