Rhynchota, an order of insects also known as the Hemiptera. The order is characterised by the presence of four naked membranous wings, by the facts that the mouth appendages are so modified as to enable the insect to feed by suction, and the caterpillar and adult stages are not sharply separated by a fixed chrysalis stage; the animal in the intermediate stage is active. The order is a very large one, numbering about 20,000 described species; the oldest known form is Eugereon, from the Permian deposits. The Rhynchota are divided into two groups: (1) the Heteroptera or Bugs, in which the front pair of wings are horny and the hind wings soft and membranous; (2) the Homoptera, in which all four wings are membranous. There are numerous families in both suborders. Among the Heteroptera the best-known forms are the Shield-bugs (or Scutelleridcc), the Chinch-bug or Blissus (one of the Lygwidai) which devastates the cornfields of America; the Bed-bugs or Cimicidre, of which the best-known English species is Cimex lectularius, which first became abundant in England after the Fire of London, when it was introduced in timber; the large Wheel-bugs (Reduvius); the Water Scorpions or Nepidw, of which Nepa cinerea (Linn.) is the largest English species, and the Water-boatmen or Notonectidcc. The Homoptera include the more interesting members of the order. The first family is that of the Cicadidre, of which there is only one English species (Cicada Anglica, Curt.); the Cicadas abound in the tropics, where their chirping enlivens the woods day and night. The Fulgoridts include the Lantern-flies and Candle-flies, some species of which are said to be luminous, though the records are not free from doubt. The frothy masses found on grass and known as "Cuckoo-spit" enclose the yellowish larva of Aphrophora spumaria (Linn.), which is the best-known member of a third family, the Cercopidce; this also includes the Froghoppers. The Plant-lice or Aphides (q.v.) form another family. The Scale-insects or Coccidce also belong to this sub-order. The females of this family produce several important products such as cochineal (yielded by Coccus cacti, Linn.) and shellac (by Coccus lacca, Kerr). Both Heteroptera and Homoptera occur in the Jurassic, and are there represented by Cicadas, Water-boatmen, etc. The Plant-lice are known first in the Wealden (Lower Cretaceous).