The malarial parasites ( Plasmodium ) exploit a wide range of vertebrate hosts, but the majority attack lizards. The population biology of lizard malaria has only recently been investigated but even so information on the invertebrate hosts are longely wanting. Of the two known cases, one is the Western fence lizard ( Sceloporus occidentalis ) of Northern California,where the invertebrate host has been identified as a phlebotominefly, Lutomyzia vexatrix . This project will study in both field and laboratory thebehavior, life history and distribution of the fly host.