318 THE entomologist's record. 



were thought to be a swarm of bees, but their true character was soon 

 discovered. They commenced their flight just as the sun was hidden and 

 continued to fly until it was quite dark. Riley adds that this species often 

 occurs in the United States, in great numbers, but that a twilight swarm- 

 ming of the nature described was hitherto unknown and bethinks that 

 the beetles must have been in search of a proper locality in which to 

 lay their eggs. In another interesting note [loc. cit., in., pp. 176-177), 

 Ragsdale states that, on September 9th and 10th, 1890, a flight ol 

 crickets, accompanied by a beetle, recognised by Riley as Ilarpalus 

 [fvavis, appeared at Gainesville, Texas, appearing to drift in an easterly 

 direction, and showing themselves abundantly on the west walls of 

 buildings. Riley further states that he had received the beetle from 

 Fort Worth, where it had appeared in the Septembers of 1886 and 1887, 

 in immense numbers. He says that the occurrence of the Harpalus 

 remains as great a mystery as the swarming of Platynus viacidicollis 

 in California, an account of which is published in the American 

 Naturalist, 1882, p. 681. In .luly 1888, the rose-beetle, Macrodartylus 

 subsj)i)iosii!i, is recorded {Imect Life, i., p. 91), as having suddenly 

 appeared in swarms at the rural grounds, New York, causing a great 

 deal of damage to grapes, roses and magnolias. The sudden appear- 

 ance of this species, possibly due, however, to local conditions and not 

 to immigration, is further commented on by Riley (lor. cit., ii., p. 297), 

 who also discusses its spread in recent years into districts where it 

 was previously unknown. 



Another interesting side of the dispersal of beetles relates to the dis- 

 tribution of aquatic forms. Darwin observes {Orij/iu of Sjwcies, p. 343) 

 that the wide-ranging power of freshwater productions can, in most 

 cases, be explained by their having become fitted in a manner highly 

 useful to them, for short and frequent migrations from pond to pond, 

 or from stream to stream within their own countries, and that liability 

 to wide dispersal would follow from this capacity as an almost 

 necessary consequence. This is particularly true of beetles, and 

 Darwin relates {Vot/ai/e of lieaiile, pp. 114, 115) that numbers of living 

 beetles, some aquatic and some terrestrial, were caught in the open sea, 

 off Cape Corrientes, seventeen miles from the coast of South America, 

 and these did not appear to be injured by the salt water. These 

 belonged to the genera Cohjmhetes, JHijdroportai, Hijdrobiiis, Notaphus, 

 CynnciiH, Aclinumia and Scarabaciis. He considered that they had 

 been floated out to sea by a small stream that drains a lake near Cape 

 Corrientes. At any rate, the circumstance of beetles swimming in the 

 open ocean seventeen miles from the nearest land is interesting from 

 the point of view of their distribution, and the possibility of their 

 dispersal by this means. The ability of certain coleoptera, normally 

 living in fresh water, to exist in a marine habitat, has several times 

 been noted. Donovan notes {Ent. Mo. May., xxii., p. 13) that, on 

 May 10th, 1885, he captured a ? of Dytisriis niaryiualis, swimming in 

 the sea at Glandore, the individual being quite at home in its salt- 

 water element. Wood records {loc. cit., p. 44) how he kept several 

 species of Hydradcphaya and Palpicornia, including the species 

 Haliplns rnjicollis, HydroporKS plauHa, Ayabiis bipustidatus and 

 Helophorus acpiaticHH in a vessel of sea-water, and that they lived 

 therein in perfect health, the three last named seeming perfectly at ease 

 throughout, although the haliplus found difiiculty in diving and 



