26o 



Beetles 



About one hundred and fifty species of Hydrophilidae are 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 somewhat, 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 obtusatus; 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 

 larvae." 



The rove-beetles, Staphylinidae, 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 country 9000 

 species are known in the world are very small. In 



FlG - 355- Larva California great swarms of minute rove-beetles dance in 

 of a rove-beetle, . . 



Xanthhlinus the air in April and May, and are a woful nuisance to 



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

 and when crushed by rubbing, their acrid body-fluids 

 both smell bad and burn. Among 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 larvae (Fig. 355) are found in the same places as the adults, and 

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

 each foot has but a single claw. The pupae 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. 



lentus. 

 Schiodte ; twice 

 natural size.) 



