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The great entomologist, Latreille,, divided this order into two primary sections to 

 which he applied the names of Geocorisa or Land Bugs, and Ilydrocorisa or Water Bugs. 

 Westwood, however, improved on this arrangement by calling the former of these 

 Aurocorisa, or Air Bugs, because there were certain species ( Hydroraetridas) which had to 

 be included in it, but which do not live on land, but pass the greater part of their time on 

 the water, although they never dive below the surface. These species were also included 

 by Latreille in his Geocorisae and called Ploteres. Westwood's arrangement of Latreille's 

 sj-stem was as follows : — 



(1.) Hydrocorisa, or those which reside in water. 



(2.) Aurocorisa, or those which breathe the free air. 



1. Ilydrocorisa. — There ai'e many species of water bugs which differ very much in 

 appearance, but they all have the antennae very short and concealed in cavities beneath 

 the eyes, their legs are modified according to their mode of life : the anterior pair are 

 short and fold close to the body, forming a pair of claw-like organs with which they seize 

 their prey ; the other legs, particularly the last pair, are generally elongated and ciliated 

 with stiff bristles which spread out when the limb is driven backward through the water 

 and so act as the blade of an oar ; of course when drawn forward they pass through the 

 water easily. The eyes are often of a large size. Nearly all the species in this group are 

 of a dull inconspicuous colour. They have to come to the surface of the water frequently 

 to obtain a supply of atmospheric air, which they carry down to the bottom again in 

 different ways ; among the Notonectidse it is carried in a space beneath the closely fitting 

 hemelytra and the upper surface of the abdomen, where it is retained by means of rows 

 of hairs. It is into this cavity that the spiracles or mouths of the breathing tubes open. 



2. Aurocorisa. — In this section the insects may be generally recognized by the greater 

 length of the antennae, and by the legs being fitted for running and walking and not for 

 swimming. Good examples of these insects are found in the destructive Squash Bugs 

 and Chinch Bugs, as well as in the useful Spined Soldier Bugs and Rapacious Soldier 

 Bugs. This, too, is the section which boasts the possession of that highly objectionable 

 creature, the bed-bug (Acanthia lectularia\ but it also includes the Reduvii, a family of 

 cannibal insects, one species of which, R. personatus, is known in Europe to feed on these, 

 and which family is represented in Canada by some useful species. 



The other sub-order of the Hemiptera is called Hemiptera-homoptera (6/aos = like, 

 Trrepa = wings), or same winged, because both the upper and under pairs of wings are of a 

 similar character ; both pairs are membranous, generally transparent and net- veined, the 

 upper larger than the lower. The wings do not lap over each other when the insect is in 

 repose as is the case among the Heteroptera, but are much deflexed at the sides and lie 

 over the back like the roof of a house. The body is generally thick and convex, rather 

 than depressed, and this partly accounts for the deflexed position the wings take when 

 not in use. With few exceptions the antennae are very short and bristle like. The face 

 is either vertical or slopes obliquely under the body, so that the beak, which is composed of 

 three joints, two short ones and one very long one, is set rather far back and issues from 

 the under surface of the head close to the breast. In nearly all it is long and slender, as 

 they all feed entirely on vegetable juices. 



Within the limits of this sub-order are included some very grotesque and curious 

 forms, and some which at first sight are apparently very dissimilar ; but which, on a careful 

 examination can easily be recognised as belonging to the same group. There are the 

 Musical Cicadaj, the well-known Lantern-flies, the active, strangely-formed little Tree- 

 hoppers and Leaf-hoppers, the Cuckoo-spit insects or Frog-hoppers, the lively Psyllidae, 

 the destructive Aphides or Plant-lice, with tlieir remarkable transformations, and the 

 extraordinary Coccidae, or scale insects, which bear a closer resemblance to vegetable 

 ■excresences than to living animals. 



None of the species have more than three joints of the feet, and Mr. Westwood con- 

 sidered this such an important character that he based his system upon it, dividing them 

 into three sections : — 



1. Trimera. Tarsi three jointed ; antennae minute, setigerous ; wings areolate. 



2. Dimera. Tarsi two jointed ; antennae, filiform, 5 to 10 jointed ; wings sub-areolate. 



3. Monomera. Tarsi one jointed ; antennae, 6 to 25 jointed ; wings not areolate. 



