The flat bugs (Hemiptera: Aradidae) are primarily mycophagous, and some species may pose a threat to cultivated mushrooms. In addition, at least one species feeds on living plant tissue. For this reason, they are potentially of economic significance. Their identification below family level is sometimes difficult, partly due to the scattered nature of the literature. We present a list of the aradids intercepted at United States Ports of Entry from 1992 to March 2013. In addition, we provide keys and diagnoses for the identification of aradid subfamilies and the intercepted, reportable genera of the Aradidae.