236 FAilILT V. GTKIXID^. 



462 (1502). Ctbistee ttmrktot.att s Say. Trans. Amer. Phil. Soc. II, 1S2.3, 

 9; ibid. II, 506. 

 Ovate, more or less wedge-shaped. Above brown with a faint greenish 

 tinge; thorax and elytra with a broad yellow margin; front of head, four 

 front legs and spots at sides of abdominal segments -3 to 6, also yellow. 

 Thorax and elytra of female, except along the suture, with numerous fine 

 short impressed lines. Length 30-33 mm. 



Tkroughoiit the State; frequent. 3Iay 27-Septeinber 20. In 

 autumn sometimes found beneath rubbish on the beaches of lakes. 



Family Y. GYRIXID.E. 

 The Whiemgig Beetles. 



In the little bays of lakes and ponds and along the quiet places 

 of flowing streams one often sees, close into shore, large colonies 

 of beetles playing and gjTating upon the surface of the stiU water. 

 These beetles are oval or elliptical in form, somewhat flattened, more 

 or less attenuate at either end and usually of a brilliant bluish-black 

 color. The name of the family is fotmded upon the principal 

 genus Gjjrinus, which in turn is derived from a Greek word mean- 

 ing "a circle," and given to these insects on account of their habit 

 of moving in little circles upon the surface of the water. They do 

 not s-nim, as commonly stated, but glide or skate upon the surface- 

 film of the water in the same manner as do the wherrjnnen or water- 

 spiders among the Hemiptera. Except when piirsued they rarely 

 dive beneath the surface, and they then carry with them a small 

 supply of air and stay but a short time. Being so agile they are 

 difficult to capture even with a net. "When handled they exude a 

 milkj- fluid which usiially has a disagreeable odor, but in certain 

 species resembles that of ripe apples, hence they are srimetinie'< 

 called "apple bugs. " 



Some of the species ot^-casionaliy crawl out of the water onto lofrs. 

 stones nr other objects, where they liask in the .sunlight. If ap- 

 proached when so engaged, the>- let go all hold and tumble, instead 

 of crawling back into the water, much in the same way as does a 

 basking turtle. "When undisturbed, the colonic-; or gi-oups are 

 ttsually massed close together, and are soinetimes almost quiescent. 

 The least alarm -vvill, however, cause a large. cLksely bunched assem- 

 bly to scatter widely in all directions. 



From the margins of these groups individuals are continually 

 darting out for a short distance, then back again. These little jour- 

 neys are probably made in search of prey, as the beetles snap vigor- 



