Abstract Molecular gut-content analysis has revolutionized the study of predator–prey interactions and yielded important insights into arthropod community processes. However, the raw data produced by most gut-content assays cannot be used to assess the relative impact of different predator taxa on prey population dynamics. They must first be weighted by the detectability half-lives for molecular prey remains for each predator–prey combination. Otherwise, interpretations of predator impact will be biased toward those with the longest detectabilities. Molecular ecologists have noted taxonomic trends in the length of the half-life, in particular that they tend to be longer in spiders, staphylinids, and true bugs. We compare new data from feeding trials of two previously untested true bugs, Geocoris punctipes (Say) (Lygaeidae) and Orius insidiosus (Say) (Anthocoridae), with those from four other heteropterans and three coleopterans, in order to test the hypothesis that half-lives tend to be longer in predato...