Fig. 13:5. Haliplidae, larvae, a, Peltodytes edentulus; b, 

 Brychius e/evatus; c, Haliplus immaculicollis, first instar; a 1 , H. 

 immaculicollis, third instar (a, Wilson, 1923; b, Bertrand, 1928; 

 c,d, Hickman, 1930). 



with fresh air; but it cannot obtain enough oxygen in 

 the water by diffusion from the coxal bubble to sustain 

 life. 



Life history. — The biology of haliplids has been 

 treated, in this country, by Matheson (1912), and 

 Hickman (1931). The immature stages of six North 

 American species have been described in detail by 

 Hickman (1930) and Wilson (1923). At least some 

 species overwinter in the larval stage, commonly in 

 damp soil above the water line. Probably all species 

 pass the winter in the adult stage. Some kinds hiber- 

 nate but others remain active even under a foot or 



303 

 Leech and Chandler: Coleoptera 



more of ice; in the latter case we do not know how 

 they obtain the rogular supplies of fresh air needei 

 for such activity. 



Adults of Peltodytes spp. lay their yellow eggs on 

 aquatic vegetation (Elodea, Ceralophyllum, and fila- 

 mentous algae). Those of Haliplus are said to bite 

 holes in the plant tissue and insert their (white) eggs 

 into the emptied cells. Egg-laying has not been re- 

 corded for Brychius or Apteraliplus. The larvae (fig. 

 lS:5a-d) are most commonly found crawling slowly on 

 and among filamentous algae, upon which they feed. 



At one time both adults and larvae were thought to 

 be predatory. Hickman and others reared specimens 

 from eggs and found larvae and adults to be veg- 

 etarian. The larvae of some species ate filamentous 

 algae (Spirogyra) which they grasped with their spe- 

 cialized front legs (fig. 13:3rf), whereas species not 

 so adapted fed on Chara and Nitella; they took animal 

 food only when starved. However, F. Balfour-Browne 

 (1940) reported that in addition to taking plant food, 

 his adult specimens fed eagerly and regularly on cut- 

 up aquatic insect larvae, crustaceans, entomostracans, 

 and fish. He quoted Beier as writing that the beetles 

 searched for oligochaete and nematode worms, and 

 even attacked mosquito and chironomid larvae. Bal- 

 four-Browne also mentions that he often found remains 

 of chitin in the oesophagus of haliplid beetles. 



The mature larva crawls up on the shore, digs into 

 a suitable spot, and forms a pupal chamber, often 

 under a stone or log. The pupa (fig. 13:3c) is a typical 

 exarate type. 



Habitat and distribution. — The species of Brychius 

 are few, but occur in both the Nearctic and Palaearctic 

 regions. Those of Peltodytes, more numerous, are in 

 the same regions and also attain the Oriental and 

 Ethiopian. The species of Haliplus comprise the bulk 

 of the family, and are found in all the above areas, as 

 well as the Australian and Neotropical regions; the 

 greatest number are in the Holarctic realm. Apterali- 

 plus is known only from California and Washington; 

 the wings are reduced and the species is flightless. 



Because they are poor swimmers except in still 

 water, haliplids are most numerous in ponds (Aptera- 

 liplus, Haliplus, Peltodytes), the sheltered parts of 

 lakes and streams or rivers (Haliplus, Peltodytes), 

 or in the current of streams and shallow rivers but 

 where stones offer shelter (Brychius, Peltodytes). 

 Few species are permanent residents of saline waters, 

 and none become adapted to hot springs. 



In North America the species of Brychius are of 

 local occurrence and until lately were rare in col- 

 lections; only two species have been reported from 

 east of the Rocky Mountains. They prefer small 

 streams with gravelly or stony bottoms. Apteraliplus 

 parvulus (Roberts) is known from San Mateo County, 

 California (though Haliplus wallisi Hatch from the 

 Grand Coulee of Washington is said to be a synonym). 

 In California A. parvulus, like certain small species 

 of Hydroporus (Dytiscidae), seems to have adapted its 

 life cycle to take advantage of ponds formed during 

 the winter rains in an otherwise dry region. The 

 greater number of species of both Haliplus and Pel- 

 todytes are found east of the Rocky Mountains, where- 



