540 HEMIPTERA. 



that kind of imago, being capable of reproduction." (West- 

 wood.) 



In Velia the triangular head is sunken in the thorax up to 

 the eyes ; the ocelli are wanting ; the thorax is large, and the 

 wings are present. 



The genus Hydrotrechus (Gerris) has the ocelli present, the 

 abdomen long and slender, while the prothorax is very large, 

 covering the mesothorax. The eggs of a European species 

 are preyed upon by a species of Teleas, according to Meczui- 

 kow. IL/drotrechus reniigis (Fig. 544) and H. rvfoscutellatus 

 Fabr. a reddish species, are abundant on our streams. The 

 larvfe are mucli shorter and with broader bodies than the adults. 



The genus Halobates has the first antennal joint as long as 

 the two following ones together ; both ocelli and wings are 

 wanting ; the mesothorax is very large, and elongated posteri- 

 orly, and the fore legs are short, outstretched, with thickened 

 femora, while the middle pair of limbs is the longest. The 

 species are found swimming on the surface of the ocean in the 

 tropics far from land. 



EEDUviiDyE (Reduvini) Latreille. The characters of this 

 family are these : head free from the thorax, elongated, nearly 

 cylindrical, with prominent eyes and two ocelli ; the antennae 

 are of moderate length, slender towards the end, and the beak 

 is stout and incurved ; the tarsi are three-jointed and the legs 

 are long and fitted for running. These insects are among the 

 most predaceous of the Hemiptera. 



The group begins Avith an aquatic genus Limnobates, which 

 connects this family with the preceding one ; it runs over the 

 surface of pools like Gerris. The body is linear ; the protho- 

 rax is as long as the rest of the thorax, and the hind wings 

 ai'e Avanting. 



Ploiaria is a remarkably slender, thread-like insect, with long 

 hair-like posterior legs, reminding us of Tipula. The species 

 are raptorial and are frequent in gardens. P. brevipennis 

 Say is reddish, with wings, and the feet are ringed near the 

 knees. Its ally, Emesa., resembles "the thinnest bits of sticks 

 fastened together," according to Westwood. The body is long 

 and thin, hair-like, and the antennae are long and delicate ; the 



