64 INSECTS AT HOME. 



with large and powerful wings, which they can vise freely; and 

 by the aid of which they can leave one piece of water and go to 

 another at will, so that a newly-formed puddle is sometimes 

 seen with several of these Beetles disporting themselves on the 

 surface. 



The life history of the Gyrinus is rather a curious one, and 

 is much the same with all the species. The eggs are deposited 

 on a water-plant, and laid in regular rows. From them, in a 

 week, or a little more, the curious larvae are hatched. One 

 of these larvae is shown on Plate III. Fig. 5. It is dirty-white 

 in colour, and has a large, flat, oval head, armed with powerful 

 jaws, and six rather long legs ; while from each side of the 

 eight last joints of the body proceeds a very slender iilament, 

 which is part of the respiratory system. The last segment has 

 two pairs of these filaments, each of which is seen, on being 

 viewed by the aid of the microscope, to contain an air-tube, 

 which passes into the body and there joins the general system. 

 When in the water its appearance is very much like that of a 

 centipede, except that the respiratory filaments have no in- 

 dependent motion, like the legs of the centipede, but trail 

 loosely in the water. 



In due time the larva is full-fed, and it then, as do manj 

 other aquatic creatures, leaves the water and crawls up the 

 stem of a water-plant, until it is several inches above the sur- 

 face. Having found a safe place, it spins for itself a small grey 

 cocoon, and there waits until it has assumed its perfect state, 

 when it breaks through the walls of the cover, and again seeks 

 the water. One of these cocoons is shown on Plate III. Fig. 6, 

 attached to the leaf of the Common Arrowhead {Sagittaria 

 sagittifolia). 



Like the Dyticidae, almost all the Whirligig Beetles exude a 

 whitish liquid of a very unpleasant odour, and are sure to do 

 so when handled. 



There are six English species of Gyrinus, some of which are 

 rarer than others. The present species, which is the most 

 common, is about a quarter of an inch in length, and blue- 

 black in colour, with a reddish mouth. The elytra are greenish 

 at the margins, and become narrowed towards the apex. They 

 are very slightly striated and punctured. 



A much rarer species is Gynnus bicolor, which must be 



