Technical Abstract: BioLure, a synthetic food attractant for Mediterranean fruit fly (Ceratitis capitata (Wiedemann)) that uses a combination of three chemical components (ammonium acetate, trimethylamine hydrochloride and putrescine), was deployed in MultiLure traps in predominantly native forests, non-native forests, farmlands, orchards and residential areas on the islands of Hawaii and Maui, to evaluate attraction of C. capitata and nontargets. Large numbers (as many as 156 per trap per day) of mainly saprophagous non-target flies (primarily Drosophilidae, Chloropidae, Lonchaeidae, Neriidae, Lonchaeidae, and Calliphoridae) were attracted to Bio-Lure. Very few predators, parasitoids or pollinators were attracted. Native species, predominantly drosophilid and calliphorid flies, were attracted in large numbers in endemic forests, but mostly (at least 88%) introduced species were collected in orchards, backyards and non-native forest. A comparison of attraction to the three separate components vs. the combined components revealed that ammonium acetate and, to a lesser extent, putrescine are the key components attractive to nontargets. Omitting the putrescine ingredient from BioLure did not drastically decrease C. capitata catches but reduced nontarget captures by 20%. These results suggest an alteration of this common attractant is warranted to reduce non-target impacts.