RHYNCHOTA. 187 



(Labidura riparia), found somewhat rarely in England along the south coast, 

 is nearly twice the size of the common species, and its forceps has a large tooth 

 beyond the middle of its length. 



Order Rhynchota. 



The numerous insects included in this order exhibit great differences in their 

 external form, and while some, such as the Flatince, rival the butterflies and moths 

 in the beauty and delicacy of their colours, others are amongst the most loath- 

 some of creatures. But whatever be their form or colour, all agree in two 

 essential characters, the first consisting in the fact that their development takes 

 place without a complete metamorphosis ; and the second that all have the 

 mouth taking the form of a beak, or rostrum, adapted for piercing and sucking. 

 The beak consists chiefly of the lower lip (labium), which is long and narrow, 

 composed of three or four joints, and grooved along the whole length of its upper 

 or anterior surface. This groove forms a sort of sheath, in which are lodged four 

 long slender blades, corresponding to the mandibles and maxillae of other insects, 

 but here transformed into piercing organs. All these parts are covered at the 

 base in front by the narrow and slightly elongated upper lip (labrum). From 

 the structure of their mouth, which is fitted only for the reception of liquid nutri- 

 ment, it is easy to infer that these insects live by piercing tissues of plants and 

 animals, and extracting the juices. The larvae differ little from the adults except 

 in size, the absence of wings, and their usually shorter and more slender antennae. 

 In many, however, the females are without wings at all stages ; and in some 

 cases both sexes are thus unprovided. When wings are present, they may be all 

 of similar texture, or the front-pair may be somewhat stiffer and less membranous 

 than the hinder. Wings of both these kinds are found in the section Homoptera. 

 In other cases, while the hind-wings are entirely membranous, the front-pair are 

 stiff and horny for some distance from their base, and thin and membranous 

 towards their extremities. Such wings, which characterise the section Heterop- 

 tera, are known as hemi-elytra. Over eighteen thousand species are already 

 known. Fossil remains of the order are found, in strata of the Jurassic epoch, 

 and are tolerably abundant in amber and other beds of Tertiary age. 



All the Heteroptera, no matter how different they may be in external form 

 or mode of life, are termed bugs, although this name was originally applied only 

 to the bed-bug and a few closely-allied species. Most are winged insects, in 

 which the fore-wings known as hemi-elytra, or simply as elytra, always have 

 the form described above. Their antennae are either short and inconspicuous, 

 as in the water-bugs, or distinctly visible as in the land-bugs, and are generally 

 composed of a small number of joints. As a rule they have two compound eyes, 

 and often two or three ocelli. The first segment of the thorax is usually large, 

 with the head sunk deeply into it. The abdomen generally has an oval flattened 

 form, and the legs are mostly slender. With few exceptions bugs are characterised 

 by a peculiar and somewhat unpleasant odour, which arises from a liquid secreted 

 by special glands placed in the front part of the abdomen, and opening to the 

 exterior by means of two small ostioles on the ventral surface of the metathorax. 



