Predaceous Stinkbugs (Pentatomidae: Asopinae)
Members of the subfamily Asopinae (common names: predatory stinkbugs or soldier bugs) are set apart from the other pentatomid subfamilies by their essentially predaceous feeding habits. Asopine first instars do not attack prey and only need moisture, mainly plant juices, to develop. Although for some predatory stinkbugs partial development on certain plant foods has been observed, nymphs from the second instar on require animal food to complete development. Further, nymphs and adults are often observed to take up plant juices or free water in addition to feeding on prey, suggesting that metabolic water or that from prey is insufficient for survival (Schumacher 1910, for more details see
). Unlike phytophagous pentatomids, predatory stinkbugs are characterized by having a crassate
rostrum. The first segment is markedly thickened and free, only the base being embedded between the bucculae. This enables a fully forward extension of the rostrum and thus facilitates feeding on active prey. The bucculae form a rostral groove that does not reach the posterior margin of the head. The rostrum generally extends beyond the coxae of the middle legs, but never surpasses the base of the venter. The scutellum is mostly much shorter than the abdomen, but in some genera it is enlarged, covering most of the abdominal dorsum. The anterior tibiae have a short, acute spine on the lower surface (Schouteden 1907; Schumacher 1910; Miller 1956; DeCoursey and Allen 1968; Thomas 1992, 1994). McDonald (1966) stated that the genitalia of the Asopinae have no unique characters, although the asopine males are unique in combining the presence of genital plates (parandria) with a thecal shield.