54 INSECTS AT HOME. 



others, and, in nearly all cases, flattened and furnished with a 

 frinire of stiff bristles on the inner side, so that they serve as 

 oars. They are jointed in a peculiar manner to the body, so 

 that there is room within the thorax for a set of very powerful 

 muscles which work them, and they are placed farther back than 

 is usual among Beetles — a peculiarity of structure which is 

 found also in the seals and the diving birds, especially the 

 penguin tribe. 



Although they cannot, as a rule, walk well, they can all fly 

 well, and are furnished with very large and powerful wings, so 

 that, if food should fail them in one piece of water, they can 

 fly to another. They generally fly at night, and have an odd 

 way, when they reach a pond or stream, of closing their wings 

 while high in the air, and allowing themselves to fall like 

 stones into the water. Sometimes, deceived by the glitter in 

 the moonshine, they have been known to fall upon the roofs of 

 greenhouses. 



Not only the Beetles, but their larvre inhabit the water, and 

 they are equally predacious in both stages of existence, the 

 larva being armed with a pair of enormous sickle-shaped jaws. 

 They are all long and narrow, and have six minute eyes, or 

 ocelli, at each side of the head. We will now proceed to our 

 examples of these insects. 



The Hydradephaga are divided into two families, the Dyticidse 

 and the Gyriuidae. There is not the least difficulty in de- 

 ciding the family to which any Water Beetle belongs, as a 

 glance at the antennse is sufficient for the purpose. The antennae 

 of the Dyticidse are long and slender, and those of the Gyrinidae 

 are stout, short, and club-like. Moreover, the first pair of legs 

 are short in the Dyticidse and long in the Gyrinidce. We 

 begin with the first family, and take an example of the typical 

 genus. 



On Plate III. Figs. 1 and 2, are seen drawings of the Great 

 Water Beetle {Dyticus marginalis). The first represents the 

 male Beetle in the act of swimming, and the second the female, 

 as she appears when flying through the air. The sexes of this 

 and other species are so distinct that in the earlier days of en- 

 tomology they were looked upon as different spec'es. As the 

 habits of this Beetle are almost identical with those of all its 



