BUGS. 271 



One more form deserves especial mention at this point, the Metrobates hesperius, 

 a native of our eastern and southern States, as well as of the Antilles. It is a merry, 

 active little insect, more plump and broad than the foregoing, of a dull, velvety blue- 

 black or dark brown color, marked on the base of the head and fore part of the pro- 

 thorax with dull yellow, the second spot being sometimes tinged with bluish-gray ; the 

 eyes are prominent and hemispherical in the unwinged adult, and it also has the pro- 

 thorax narrow, somewhat like a neck, but in the winged state the prothorax caps over 

 the base of the head between the eyes, and is only faintly marked off from the broad 

 niesothoi;acic scale by a feeble sinuated suture. All the upper surface of the body is 

 more or less velvety pubescent; the dorsal scale is bluntly rounded at tip, and feebly 

 sinuated each side; while the wing-covers, when at rest, are narrowerthan the thorax, 

 gradually decrease in width towards the tip, project far beyond the end of the venter, 

 have a thick corium with two elongated cells, bounded by stout veins, and a mem- 

 brane more than twice as long as the latter, which has a stout vein running parallel 

 to the inner and outer margins, and continuing around tlie apex as a loop, and along 

 the middle the vein-like line forms a suture throughout the whole length of the mem- 

 brane. The antennae are thick, the basal joint curved, slender at the inner end, 

 longer than the three others conjoined, acuminate at tip exteriorly; the second and 

 third short, abruptly thickened at tip. The posterior tarsi are one-jointed, slender ; 

 and the nails of the stout anterior tarsi are placed about one-third of the length from 

 the tip. 



This species is larger and stouter than the preceding, and, when full gi-own, 

 measures about one-fifth of an inch to the end of the abdomen. Like the Stephania, 

 it moves very rapidly over the surface of the water by rowing with its long middle 

 legs, and has the same habit of jumping from the water to grasp mosquitoes, flies, and 

 other insects. Both of these insects imitate the larger Zimnotrechus, etc., by diving 

 beneath the surface when frightened or pursued. The eggs are attached to the project- 

 ing twigs, leaves, and stems of water-plants during early summer, and by the middle 

 of that season countless multitudes of the young may be seen in company with the 

 adults on the bayed-out, quiet parts of our inland streams. No winged specimens 

 have yet been found in the United States, but in the Island of San Domingo both 

 forms live in company on the surface of the rivers. 



A closely related family, Veliid^, occupies the next place, and is composed of 

 insects having a form combining to some degree the characters of the foregoing group 

 and those of the more advanced Hemiptera. Here the body is short and deep, with 

 shorter limbs, mostly adapted for running over the water, rather than for rowing. 

 Like the preceding, they pass most of their time upon the surface of the water, but 

 always near the banks of the stream or pond, but they also make excursions beyond 

 the limits of the water, and move with great freedom upon the land. The head is set 

 closely into the prothorax, with the eyes round, projecting a little each side, and the 

 face either short, convex, or produced into a thick, blunt cone. A three-jointed 

 rostrum, recalling that of Salda, but thicker, extends horizontally backwards to 

 beyond the fore-coxse, the second joint of which is longer than all the others united. 

 The antennse are four-jointed, either short and quite stout, or having one or two basal 

 joints thick, and the following ones very slender. The prothorax and mesothoracic 

 cover are scarcely separated ; the latter is free and more or less protracted backwards, 

 either blunt or triangular. In some genera the two pairs of hind tarsi are split; 

 in others they are entire, and the curved nails are placed next the tip. The number 



