SUB-ORDER II. PLANIPENNIA Veins with evident forking at the margins of the wings: vein Rs usually with numerous branches. Larvae with piercing mouth parts: pupae enclosed in a cocoon.
Included here are the major portion of the Neuroptera: they are nearly all terrestrial insects, only a small number being partially or truly aquatic in their larval stages. The Planipennia are divided into 16 families of which only the most important are mentioned.
The Ithonidae or moth-lacewings are confined to Australia : they are large, stoutly built, moth-like insects with primitive vena tion. Their larvae live in the soil where they prey upon those of chafer beetles, to which they bear a close general resemblance. The Hemerobiidae or brown lacewings are widely distributed and fairly numerous in species. Their larvae along with those of the Chrysopidae or green lacewings (fig. 1) roam about vegetation preying upon aphides, mites, thrips and other soft-bodied insects (see LACEWING-FLY). The Osmylidae and Sisyridae have aquatic larvae : the insects of the first mentioned family are medium to large-sized species which differ from the lacewings in certain venational characters. Osmylus chrysops is the largest British Neuropterous insect and occurs locally along the borders of streams where there is dense vegetation. The Sisyridae differ in having very few cross-veins to the wings besides being much smaller in size. They are brown or fuscous insects found along the borders of rivers which contain the fresh-water sponge upon which their larvae feed and live. Three species of Sisyra occur in Britain and this genus, along with Climacia, is found in the United States. The Mantispidae or mantis flies (q.v.) are easily distin guished by the elongate thorax and the prehensile fore-legs which resemble in form those of the common mantis (q.v.) and are like wise used for seizing other insects which serve as their prey. The larvae of the European Mantispa styriaca are predacious upon young Lycosa spiders and during development they undergo strik ing changes of form constituting hypermetamorphosis. The family
is mainly tropical but ranges into southern Europe and a few rare species occur in the United States. The Psychopsidae have very broad, rounded wings supported by a stout "mid-rib" and with a densely reticulated venation. Many are insects of striking beauty and their larvae have been found beneath bark of trees. The family has a wide discontinuous range occurring in South Africa, Tibet, China and Australia. The Nemopteridae (fig. 2) differ from all other Neuroptera in having very long thread-like or ribbon-like hind wings. Their larvae occur in caves on the floors of buildings among debris, etc., where they prey upon smaller forms of insect life. The family occurs in many of the warmer parts of the world including southern Europe but is absent from North America. The Myrmelionidae or ant-lion flies (q.v.) bear a general resemblance to dragon-flies and have short knobbed feelers. Although most abundant in the warmer parts of the world, several species occur in Europe, one being found as far north as Sweden, but none are found in the British Isles : about 6o species inhabit the United States. Their larvae live on the ground where some make pit-like snares for entrapping their prey, while others hide away under stones or debris. The Ascalaphidae are closely related to the pre ceding family but can easily be separated by their much longer antennae as well as by venational differences. Their larvae either hide away on the ground or live concealed on the bark of trees. They are chiefly tropical insects only a few species occurring in southern Europe and North America. The Coniopterygidae, or mealywings, number about 5o species and are the smallest and most aberrant of all Neuroptera. They are covered with a white powdery secretion, their wings have comparatively few veins and the hind wings are much reduced in size. Their larvae roam about plants, preying upon aphides, scale-insects and mites. Rather more than half a dozen species are found in Britain and a similar number occur in the United States.