2i6 INJURIOUS AND USEFUL INSECTS 



Family Carabidae (ground-beetles). All the legs adapted for 

 running. 



There are many species of the same general structure and 

 mode of life. We see them run across the paths of a garden 

 or field ; we notice their agility, their long legs, their slender 

 antennae, and their habit of lurking by day in hidden recesses. 

 A few species, however, are bold enough to show themselves 

 freely. Black or dark colours are prevalent, but some are gay 

 with metallic hues. The tarsi are always five-jointed, and the 

 jaws are adapted to piercing. Some of them eject an acrid 

 liquid when handled. 



Family Dytiscidse (diving-beetles). Hind legs adapted for 

 swimming. 



Dytiscus marginalis is described in Lesson 6. 



Sub-order III. — Clavicornia (clavicorn beetles) 



Tarsus five-jointed in all the legs (many exceptions occur). 

 Antennas often clubbed. An unsatisfactory division. 



Family G-yrinidse (wMrligig-beetles). Feelers short. The 

 compound eyes divided into two pairs unHke in structure. 

 Middle and hind legs short, broad, adapted for swimming. 



Family HydropMlidse (water scavenger-beetles). Feelers 

 short, clubbed. Palps long, resembling antennae. There are 

 two sub-families : — 



1. Sub-family HydropMlinse. Legs fringed. First joint of 

 tarsus of hind leg very short. Aquatic beetles. 



2. Sub-family Spliaeridiinse. Legs not fringed. First joint 

 of tarsus of hind leg long. Terrestrial or partially aquatic 

 beetles. 



Family Silphidae (carrion-beetles). 



Family Staphylinidae (rove-beetles). Wing-covers short, 

 exposing most of the abdomen, whose segments are very mobile. 



To this family belongs the devil's coach-horse, or cocktail, a 

 common beetle, well-known to schoolboys, who see it running 

 on pathways, or turn it out from beneath large stones. It is 

 about an inch long, and of a dull black in every part except 

 the tip of the antenna, which is rust-coloured. When 

 threatened, it opens its jaws, erects its tail like ai scorpion, and 

 looks as terrible as its size permits. At the same time it dis- 

 charges from a pair of glands at the tip of the tail a fluid, 

 which volatilises immediately and diffuses a pungent odour. 



