THE CANADIAN tlNTOMOLOGlST. 177 



Many an entomologist wlien drinking from a field or roadside spring 

 has noticed the tiny black, silver spangled insects that detach themselves 

 from the stones forming the basin and rim across the surface, or glide out 

 from the side and swiftly curve in to their former resting places. This is 

 Microvelia americana Uhler. It is to be found on the banks of any body 

 of water, moving or still. Where the walls of the spring or the bank of 

 the stream or pond are more or less vertical, they perch a little above the 

 water. But on shelving or sloping banks they wander about over the 

 mud or pebbles seeking their prey, leaving the shore only when alarmed 

 or disturbed. They also conceal themselves under overhanging banks of 

 streamlets, as observed by Uhler in Maryland and the writer in New 

 Jersey. I have found them perched on logs jutting out from the shore, 

 and among the heaps of brush and twigs that gather in the slack waters 

 and eddies of streams. In such places they pass the time from earliest 

 spring till the bleak days of late autumn. I have secured adults just 

 emerged from their hibernacula as early as March, and as late as the end 

 of September have seen adults and nymphs, and in mid-October adults 

 only. From then on, according to Uhler, " they hibernate in colonies 

 beneath the overhanging banks of little streams (in the Middle States) '"^ 

 until the first warm days of spring entice them from their shelter, They 

 must begin to breed at once, because, again quoting Uhler, " by the latter 

 part of June they have become fully winged." I have myself noted the 

 young in May, and taken nymphs arriving at the adult toward the end of 

 July, which perhaps is as early as is noimal in the latitude of New York. 

 Of course, their precise time of appearance in the spring, and of seeking 

 hibernacula on the approach of winter is largely governed by the tempera- 

 ture, and naturally varies with the latitude and the variations of the 

 thermometer. 



All the water-striders, large and small, are carnivorous, and Microvelia 

 is no exception to the invariable rule. In nature they doubtless feed on 

 such small insects as are tiny enough to be overpowered, such as Spring- 

 tails, larvre of flies, and other soft-bodied and feeble forms, or on those 

 larger ones which are drowned in their haunts. In the aquaria they have 

 been fed on house-flies, and where there liave been water-fleas in the 

 water, they have feasted on the unlucky ones imprisoned in the surface 

 film. Like all the predaceous Heteroptera, they are always in a condition 

 of semi-starvation, and when a living fly is fed them, of course they attack 



6. Standard Nat. Hist., II, p. ^75. 



