38(5 NATURAL HISTORY OF ARTHROPODS. 



Dr. Le Conte says of the hoetles of this family: "These are small, shining, usuallv 

 ovate, sometimes slender insects of a brown color, more or less clothed witli erect 

 hairs. They are found variously near water, under stones, in ants' nests, and under 

 bark, and are frequently seen tlying in the twilight." 



A small jiortion of the Coleoptera with claviform antennte have the dorsal seg- 

 ments of the abdomen entirely corneous and the elytra very short, not covering the 

 abdomen. Of this jiortion the Pselaphtd.e have tlie abdomen rigid and the ventral 

 segments live or six in number. The anteiiiue have from one to eleven joints, the 

 labial palpi are very short, the maxillary palpi are usually long and four-jointed, eyes 

 are sometimes absent, claws simple .-nid frequently single, wings often wanting. The 

 species of this family are all very small and many are myrmecophilous, living on 

 friendly terms with ants. As cause for this friendly relationshiji, it is said that eei- 

 tain species of Pselaphidie secrete, as do the Aphida', fluids which the ants eat. This 

 kind of life has been so long participated in l)y these l)eetles that many species are 

 blind, and are fed, carried about, and j)rotected by the ants exactly as they care for 

 their own larviv; this is the case with Clarifjer fci'*tac'e«.<t, a Eurojiean sjjecies whicli 

 has connate elytra and is a])terous. Certain species of tliis family live in caves, .md 

 one of them, Jifachcrn'tex ■■iiihtefraneun, is jieculiar in liaving males with eves and 

 females without these organs. In Artirerics, of which several species are found in 

 Australia, the anteniup are one-jointed. In the North American genera, Adirmes 

 and J^ustiffei; the antenna' have but two joints, and in the former geinis, eyes are 

 wanting. 



The Stai'IIVLIMD.e, which, like the Psclajihida', have short elytra, differ from the 

 latter family in having the abdomen flexible and consisting of eight ventral segments. 

 While including many minute forms, tliis family also includes some species that are 

 an inch or more in length. The antennae are generally eleven-jointed, but are variable 

 in form and insertion, the labial palpi are usually three-jointed, the maxillary pal]ii 

 generally four-jointed. The short tiaincate elytra usually leave most of the abdomen 

 exposed ; and when these beetles are disturbed, many of them turn the tip of the abdo- 

 men over the bodv as if intending to sting. Some of them discharge odorous defensive 

 fluids from the U\> of the abdomen when tiiey have assumed this threatening ]iosition. 

 The wings, when present, can be closely packed away beneath the short elytra. In 

 Pachycorinvs dimorphus from New Zealand, Mr. A. Tauvel has noticed that the 

 females are dimorphic, the form that has normal eyes has longer elytra and wings, 

 while the partly-blind form lias very short elytra and no wings — a curious correlation 

 of locomotion .and sight. Some species of Sta]ihylinid;e have, in addition to the com- 

 pound eyes, a pair of ocelli. 



The larvae of Staphylinida> resemlile the imagos more than is usual 



with Coleopterous larvae, chiefly on account of the larval-like apjiearance 



of the imagos themselves. The antenna' are always four-jointed, 



although apparently five-jointed in some genera. The mouth-parts 



are well developed, the maxillary palpi are of three or four joints, the 



ocelli vary according to genera from one to six on each side, the body 



is elongate and is usually armed at the anal end with a pair of append- 



^'''o/of^'Ms^'*" ^S^^ which are mostly two-joiuted. These agile larva:" are of a firm 



texture, of a brownish black or yellowish color, and they pu]iate, for 



the most jiart, underground or beneath rubbish on the ground. In many forms tlie 



metamorphosis lasts but one year. 



