388 



NATURAL HISTORY OF ARTHROPODS. 



Numerous species of the genera Bledius, Cryptobium, Lathrobium, Philonthus, 

 Quedius, Aleochara, and llomalota are found in the United States, but their specific 

 and even their generic determination is often difficult. Aleochara 

 brachypt&rus, which is figured, occurs both in Europe 

 and in North America. 



The family PLATYPSTLLID^E consists of a single 



/ O 



species, Platypsylla castoris, an ovate, elongate, 

 much-flattened jiarasite of the beaver (Castor fiber). 

 The beetle is only 0.16 of an inch long, and has 

 neither eyes nor wings; the elytra are short, leav- 

 ing five abdominal segments exposed. This insect was first 

 described by Ritsema in 18G9 as a new genus and species of 

 Aphaniptera, but its coleopterous nature was pointed out in 1872 

 by Dr. J. L. Le Conte. Professor J. O. Westwood considers it to represent a distinct 

 order of insects, the Achreioptera. 



With the family HYDKOPHLLIDJE begins a series of several families of Coleoptera 

 which inhabit water, or, in a few cases, extremely moist places. Of these families only 



FlG. 459. Aleo- 

 chara bracltyp- 

 terus. 



FIG. 460. Platypsylla 

 castoris. 



Fiu. 401. Hydropliilus piceus, larva, male, female, and egg-nest. 



the Hydrophilidne have clavate antenna 3 . The antennas have from six to nine joints, 

 the outer joints forming a distinct club, the palpi are long, the middle and posterior 

 legs are sometimes flattened and fitted for swimming. The images of this family are 

 said to eat vegetable matter, either decomposed or living, and this is probably true of 

 many species; but certain kinds of -fTi/drop/tilus prefer animal matter when they can 

 obtain it. Robert writes that Jf. piceus feeds upon snails (Limnceus), and I found that 

 this species ate greedily fresh meat or fish in preference to vegetable matter in an 

 aquarium. Westwood asserts, however, that H. fennicus eats turnip leaves in the 



