The Palaeodictyoptera are an extinct order of medium-sized to very large, primitive Palaeozoic paleopterous insects.
They were characterised by beak-like mouthparts, and similarity, between their fore- and hind wings, and an additional pair of winglets (large paranotal lobes) on the prothorax, in front of the first pair of wings. Although the paranota are technically not wings, the Palaeodictyoptera are whimsically called "six-winged insects". The actual wings are often boldly marked, the colour patterns evident even in fossils.
The mouthparts were elongated, and included sharp piercing stylets, and possibly a sucking pump-like organ. Unlike modern sucking insects, such as the Hemipterans, the mouthparts were held vertically below the head, or projected forwards. They probably used these organs to suck juices from plants, although some may have been ectoparasites, or predators.
Some types attained huge size. For example, Mazothairos had a wingspan of about 55 centimetres (22 in). Another distinctive feature was the presence of unusually long cerci, about twice the length of the abdomen.
The Palaeodictyoptera are a paraphyletic assemblage of basal palaeodictyopteroidean insects, rather than a clade, because they gave rise to other insect orders.[clarification needed conflicts with normal definitions of 'clade' and 'monophyletic'] They range in time from the Middle Carboniferous (late Serpukhovian or early Bashkirian in age) to the late Permian.