We describe the larval stages of Lixadmontia franki Wood & Cave (Diptera: Tachinidae). The fly is a specialist parasitoid of bromeliad-eating weevils and a potential biological control agent for controlling an invasive bromeliad-eating weevil, Metamasius callizona (Chevrolat) (Coleoptera: Curculionidae), in Florida. Morphological characteristics that can be used to distinguish the instars of L. franki, including the mouth hook and cephalopharyngeal skeleton, body size and color, spinulae patterns, and presence and structure of spiracles, are described, measured, and illustrated. Fly larvae live in the host's body cavity and attach their caudal end to the host's tracheal tubes. The first instar builds a respiratory funnel and the second instar remains attached to the same point and builds upon the funnel. The third instar does not build upon the respiratory funnel. The third instar disconnects from the respiratory funnel shortly before exiting the host. First and second instars are metapneustic, but the third instar is amphipneustic.