26o 



Beetles 



About one hundred and fifty species of Hydrophilidx arc known in this 



country. The largest species belong to the genus Hydrophilus, are shining 



bluish or greenish black, and measure nearly two inches in length. "In the 



genus Hydrocharis the metasternum is prolonged somew^hat, but does not 



form a long, sharp spine as in Hydrophilus and Tropisternus, and the sternum 



of the prothorax bears a keel-shaped projection. Our most common species 



is Hydrocharis ohtiisatus; this measures about five-eighths of an inch in 



length. 



" Some of the smaller species of this family are not aquatic, but live in 



moist earth and in the dung of cattle, where, it is said, they feed on dipterous 



larvK." 



The rove-beetles, Staphylinida;, form a large family, numerous in species 



and individuals over the whole country, and one whose members are readily 



recognized by the elongate flattened soft body, narrow and parallel sides, 



with short truncate leathery elytra under which the hind 



wings are compactly folded so as to be wholly concealed. 



They are mostly carrion-feeders and with the Silphidae 



(p. 261) are almost sure to be found whenever a mass of 



decaying flesh or excrementitious matter exposed on the 



ground is turned over. They run swiftly when disturbed 



and curve the tip of the flexible abdomen up over the 



body in a sort of threatening way, as if they would sting. 



They cannot; they can simply smell bad. Although the 



more familiar rove-beetles are of fair size, from half an 



inch to nearly an inch long, the majority of the one 



thousand or more species found in this countrv — 9000 



species are known in the world — are very small. In 



'^'G; 3S.';- Larva California great swarms of minute rove-beetles dance in 

 of a rove-beetle, ,..■,.,,,, , , , . 



Xanihalinus the air HI .\pril and May, and are a woful nuisance to 



lentus. (After people driving or bicycling. They get into one's eyes, 



natural size ) ^""^^ when crushed by rubbing, their acrid body-fluids 



both smell bad and burn, .\niong these smaller Sta- 



phylinids are numerous predaceous species and many which are found in 



flowers, probably feeding on pollen. Others are found on fungi, on mud, 



and in other damp places, and some live in ants' nests (see Chapter 



XV, p. 55.). 



The larva? (Fig. 355) are found in the same places as the adults, and 



are elongate, narrow-bodied, and rather like those of the Carabidx, but 



each foot has but a single claw. The pup;c of some species are enclosed 



in a sort of exudation that dries into a firm protecting coating rather like 



the horny cuticle of a lepidopterous chrysalid. 



Among the more familiar rove-beetles are species of the genus Creophilus. 



