320 INSECTS. 



One, Hydrometra stagnorum, an insect very common 

 on all stagnant water, is remarkable for extreme slender- 

 ness, being scarcely thicker than a fine thread, and about 

 three-eighths of an inch in length. The head is very long, 

 the eyes are excessively prominent, and the wing-cases 

 do not overlap. Gerris lacustris, and Gerris paludum 

 (PL XIII., fig. 3), two other common species, are larger 

 and somewhat bulkier, and are very conspicuous as they 

 skate on the water with the utmost swiftness and ease of 

 motion. Velia rivulorum is a rather less common insect, 

 shorter and not so slender as the last, and of livelier 

 colouring, black, red, and white 



There are five genera in this family. 



The third family, Reduviidse, contains genera and 

 species varying much in figure and general appearance, 

 but to be recognised by the short, thick, curved beak, 

 the neck-like form of the back of the head, and the 

 long antennae with the last joint very slender. The 

 larvae of one species in this family, Reduvius personatus, 

 has the curious habit of thickly covering itself with 

 dust, so as almost to lose the appearance of an insect. 

 A similar habit has been already described in the larvse 

 of the Tortoise Beetle. Eeduvius personatus is found 

 indoors, and is said to prey on the Bed Bug. Some 

 of the family do not, except under peculiar circum- 

 stances, fully develope their wings and wing-cases. 

 There are six genera in this family. 

 Cimicidse, the fourth family, enjoys the distinction of 

 containing the Bed Bug. There is one genus, in which 

 are four species. These are all very flat, roundish in 

 outline, and even in the perfect state have but the indi- 

 cation of one pair of undeveloped wings, consisting of 

 two little scale -like appendages. 



