Technical Abstract: The water primrose flea beetle Altica litigata (family Chrysomelidae) is a known insect pest to several nursery plants due to its aggressive feeding behavior – typically carried out in significant numbers. This aggregate feeding usually results in severe defoliation of their host plant. However, because of this tendency to defoliate its host other flea beetles within the same family of insects are used as biocontrol agents of the invasive weed, leafy spurge. Despite the apparent conflicting economic adversity to nursery plants and the potential environmental benefits there are few reports on the chemical communication (semiochemical) of this family of insects. Creeping water primrose (Ludwigia hexapetala) is an invasive aquatic weed in California wetlands and is a host of A. litigata. The volatile emissions of the flea beetle were collected while they were: 1) in containers by themselves; 2) in containers with L. hexapetala leaves; 3) in situ on L. hexapetala leaves in a growth chamber; and, 4) in situ on L. hexapetala leaves in the field. Two volatile chemicals identical to other known compounds from different flea beetle species were detected from A. litigata.