Asopinae

Asopinae can be distinguished from herbivorous Pentatomidae by their predatory mouthpart morphology: hook-shaped mandibular teeth with five irregular teeth and three long pointed hooks at each stylet tip, and maxillae with small teeth and short barbs along the food canal edge. The labrum is triangular and elongated, and the four-segmented labium is often longer than in herbivorous relatives. Many species exhibit vivid coloration with orange, black, or metallic patterns, though color variation exists within species. The foretibiae in some genera bear foliaceous expansions. Unlike herbivorous stink bugs, Asopinae lack mouthpart adaptations for plant feeding and possess sensilla specialized for detecting prey rather than host plants.

Asopinae species occupy diverse habitats including agricultural fields, forests, and tropical to temperate ecosystems. In agro-ecosystems, they are associated with crops where prey populations occur, including potato fields and vegetable gardens. Some species have shown range expansion into previously thermally limited regions, including regular incursions as far north as New Hampshire and the Dakotas in North America. The subfamily exhibits broad geographic distribution across the Neotropical, Afrotropical, Palearctic, Oriental, and Nearctic regions.

Asopinae has a global distribution spanning tropical, subtropical, and temperate regions. Documented occurrences include: North America (with range expansion noted in warming climates), South America (particularly diverse in French Guiana, representing approximately 20% of South American Asopinae diversity), Africa (including Ethiopia, Senegal, West Africa, South Africa, Uganda, Congo region, Seychelles, Madagascar, Cabo Verde, Sierra Leone, Nigeria, and other regions), Asia (Philippines, Bhutan), and Brazil. The subfamily shows highest diversity in the Neotropics.

Activity patterns vary by species and region. In mid-western plains agro-ecosystems, peak abundance occurs from May to August, with population surges in June coinciding with lepidopteran larval availability. In temperate North America, adults may be observed through autumn until killing frosts. Some species show increased activity following warm winters, with developing nymphs and adults present throughout summer and autumn in regions with extended growing seasons.

Asopinae are obligate predators feeding primarily on slow-moving, soft-bodied insects, especially larval forms of Lepidoptera. Documented prey includes: caterpillars, Colorado potato beetle (Leptinotarsa decemlineata) eggs and larvae, leaf beetles (Chrysomelidae including Platyphora species), brown marmorated stink bugs, kudzu bugs, fall armyworm (Spodoptera frugiperda), and velvetbean caterpillar (Anticarsia gemmatalis). Some species also prey on beetles in families Erotylidae and Endomychidae. Prey location involves detection of volatile compounds released by plants damaged by herbivore feeding.

Asopinae are active hunters that locate prey using olfactory cues, specifically detecting volatile sesquiterpenoids released by plants damaged by herbivore feeding. Upon encountering prey, they impale the victim with their beak and immobilize it with toxic venom, then inject digestive enzymes to liquefy tissues before sucking nutrient-rich fluids through a muscular pump in the head. Pre-attack behavior includes restless rubbing of antennae and forelegs together, possibly representing grooming or assessment behavior. Males have been observed guarding mates for extended periods. Some species exhibit Müllerian mimicry.

Asopinae function as important natural enemies of agricultural and forest pests, contributing to biological control of lepidopteran larvae, beetle larvae, and other herbivorous insects. In agro-ecosystems, they help regulate populations of crop pests including Colorado potato beetle and various caterpillar species. Their presence is associated with reduced pest damage in some systems. Population dynamics are closely tied to prey availability, with surges in predator numbers following increases in herbivore populations.

Asopinae are valued as biological control agents in integrated pest management programs, with several species deployed or encouraged for control of agricultural pests. The two-spotted stink bug (Perillus bioculatus) and Florida predatory stink bug (Euthyrhynchus floridanus) are notable examples used against Colorado potato beetle and other crop pests. Their effectiveness is enhanced by their ability to locate prey through plant volatile cues. Climate change has facilitated range expansion of some beneficial species into previously unsuitable northern regions, potentially expanding their utility in pest control.

• Pentatominae (herbivorous stink bugs)Herbivorous Pentatominae share general body plan and defensive scent glands with Asopinae, but differ fundamentally in mouthpart morphology (lacking raptorial hooks and teeth), diet (plant feeding), and ecological role. Asopinae possess specialized predatory mouthparts with mandibular hooks and maxillary barbs absent in herbivorous relatives.
• Reduviidae (assassin bugs)Both are predatory Hemiptera with raptorial forelegs in some groups, but Reduviidae belong to a different infraorder (Cimicomorpha vs. Pentatomomorpha for Asopinae), typically have three-segmented tarsi, and lack the shield-shaped body and scent gland system characteristic of Pentatomidae. Asopinae have the triangular scutellum typical of stink bugs.

• BugGuide
• Wikipedia
• iNaturalist taxon
• NCBI Taxonomy
• Bugs in Orange and Black, Part II: A spooky southern predator heads north in a warming world – Florida predatory stink bug, Euthyrhynchus floridanus — Bug of the Week
• Bugs in orange and black, Part 3 – Trick or treat? Two-spotted stink bug, Perillus bioculatus, has a lethal trick that turns Colorado potato beetle, Leptinotarsa decemlineata, into a tasty treat — Bug of the Week
• First catalogue of the Asopinae (Hemiptera, Pentatomidae) from French Guiana
• Revision of Tynacantha Dallas with description of two new species (Hemiptera: Heteroptera: Pentatomidae: Asopinae)
• Revision of the African shieldbug genus Afrius Stål, 1870 (Hemiptera: Heteroptera: Pentatomidae: Asopinae)
• Delimiting Cantheconidea Schouteden 1907, with the description of a new genus (Heteroptera: Pentatomidae: Asopinae)
• Meiotic behaviour of chromosomes in three predator species of the subfamily Asopinae (Heteroptera: Pentatomidae)
• Revision of Heteroscelis Latreille, 1829 (Heteroptera: Pentatomidae: Asopinae) with the description of a new species from Colombia
• Revision of genus Stilbotes Stål (Hemiptera: Pentatomoidea: Pentatomidae: Asopinae) with description of a new species 
• Comparative Morphology of the Mouthparts in Three Predatory Stink Bugs (Heteroptera: Asopinae) Reveals Feeding Specialization of Stylets and Sensilla
• Does it make scents? Making a case for the extirpation, and possibly extinction, of the native stink bug Rhacognathus americanus (Pentatomidae: Asopinae)
• Study of Ecological Diversity of Predatory Asopinae Bugs in the Agro-ecosystem of the Mid-Western Plains