The Lygaeidae are a family in the Hemiptera (true bugs), with some 60 genera in six subfamilies. The family includes the insects commonly known as milkweed bugs, and also some of those known as seed bugs. The family used to be vastly larger, as numerous former subfamilies have been removed and given independent family status, including Artheneidae, Blissidae, Cryptorhamphidae, Cymidae, Geocoridae, Heterogastridae, Ninidae, Oxycarenidae, Pachygronthidae, and Rhyparochromidae, which together constituted well over half of the former family. Many of the species feed on seeds, although some feed on sap (mucivory), and a few, such as the wekiu bug, feed on insects.
The bizarre and mysterious beetle-like Psamminae were formerly often placed in the Piesmatidae, but this is almost certainly quite incorrect. Their true affiliations, however, are not entirely resolved to satisfaction.
Subfamily Ischnorhynchinae (this subfamily is occasionally treated at the family level)
Insects (from Latin insectum, a calque of Greek ἔντομον [éntomon], "cut into sections") are a class of invertebrates within the arthropod phylum that have a chitinous exoskeleton, a three-part body (head, thorax and abdomen), three pairs of jointed legs, compound eyes and one pair of antennae. They are among the most diverse groups of animals on the planet, including more than a million described species and representing more than half of all known living organisms. The number of extant species is estimated at between six and ten million, and potentially represent over 90% of the differing animal life forms on Earth. Insects may be found in nearly all environments, although only a small number of species reside in the oceans, a habitat dominated by another arthropod group, crustaceans.
The life cycles of insects vary (from one day to a few years), but most insects hatch from eggs. Insect growth is constrained by the inelastic exoskeleton and development involves a series of molts. The immature stages can differ from the adults in structure, habit and habitat, and can include a passive pupal stage in those groups that undergo complete metamorphosis. Insects that undergo incomplete metamorphosis lack a pupal stage and adults develop through a series of nymphal stages. The higher level relationship of the hexapoda is unclear. Fossilized insects of enormous size have been found from the Paleozoic Era, including giant dragonflies with wingspans of 55 to 70 cm (22–28 in). The most diverse insect groups appear to have coevolved with flowering plants.