Fourteen islands within the Boston Harbor Islands national park area were surveyed for Lepidoptera, Odonata, and tiger beetles (Coleoptera: Carabidae: Cicindelinae) on 67 nights during 2001 and 2002 as part of a five-year inventory of the natural resources of the park. A total of 394 macrolepidopteran species and 166 microlepidopteran species were documented nocturnally, and 51 species of butterflies, 10 of odonates, and 1 tiger beetle were observed during the daytime. Two moths listed in the Massachusetts Endangered Species Act were documented: Spartiniphaga inops (Grote) (Lepidoptera: Noctuidae: Amphipyrinae) and Abagrotis nefascia (J.B. Smith) (Noctuidae: Noctuinae). S. inops is resident on Worlds End, and A. nefascia on Lovells Island. Although two grassland-affiliated genera, Apamea Ochsenheimer (Noctuidae: Amphipyrinae) and Leucania Ochsenheimer (Noctuidae: Hadeninae), were well represented (13 and 8 species, respectively), the total number of macrolepidopteran species was low given the sampling effort and variety of habitats surveyed. Ambient light from Boston and surrounding cites as well as the high percentage of non-native vegetation on many of the islands are two possible factors, in addition to island biogeographic effects, resulting in reduced diversity.