Palaeodictyoptera

The Palaeodictyoptera were large flying insects which are now extinct. They were common in the Upper Carboniferous, and became extinct at the end-Permian extinction. Their size varied from large to huge. For example, "Mazothairos" had a wingspan of about .
Herbivores.
They were the first major group of herbivorous insects. They had long, beak-like, piercing mouthparts, and probably a sucking organ. The mouthparts match the signs of damage in fossil plant leaves and stems.
Flight.
In addition to the normal four wings, they had two "pronota" in front. These pronota were smaller than the regular wings, but had wing veins just like the real things. They did not move up and down, so maybe they helped gliding. The Palaeodictyoptera are sometimes whimsically called "six-winged insects". The actual wings are often boldly marked: the patterns of colour can be seen in fossils.
These insects had paired "cerci" (singular: cercus) on their rear segment. The function of these is not clear. Cerci often serve as sensory organs, but they may also be used as weapons or copulation aids, or they may simply be vestigial structures. The cerci on some species was longer than the rest of the insect.