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BELOSTOMID^ AND OTHER FISH-DESTROYING BUGS. 



By George Dimmook. 



Insects are generally considered to be beneficial to fishes by 

 furnishing them one of the most unfailing sources of food. There 

 are, however, a few insects which are injurious to fishes, thus 

 making an exception to the rule. DeGeer published a statement, 

 in 1774, that the larvae of dragonflies (Libellulidse) would seize 

 and kill fishes, a statement confirmed by Dale in 1832. Von 

 Miitzschefahl, in 1778-79, mentions several aquatic insects 

 which attacked the Perch, among them two species of water- 

 beetles (Dytiscidse) and two species of water-bugs {Notonecta 

 glauca and Nepa linearis, now called Ranatra linearis). The 

 destruction of young fishes by water-beetles has since been 

 noted by Elles in 1830, by Dale in 1832, and by Riley in 1885. 

 In regard to the water- bugs, observations published within the 

 past few years have not only confirmed the above-mentioned 

 earlier statements, but other bugs have been discovered to attack 

 fishes. Leidy, as early as 1847, writes that species of Belostoma 

 and Perthostoma (Zaitha) prey upon fishes. Glover, in 1875, 

 states that Ranatra quadridenticulata and Belostoma americanum 

 feed on small fishes, and that Nepa apiculata probably, and 

 Notonecta instdaris possibly, do the same. Milner, in 1876, writes 

 that Belostoma grande captures and eats fishes. Miss Ormerod, 

 in 1878, describes how Ranatra linearis attacks fishes ; the same 

 year Peck called attention to the destruction of the eggs of Carp 

 by the same insect. Turner, the next year, mentions the killing 

 of young Sticklebacks in an aquarium by Belostoma. Leonard 

 notices the showing, at the Edinburgh Fisheries Exhibition in 

 1882, of a preparation by Hugh D. McGovern, of Brooklyn, 

 N. Y., of a year-old Trout, " surmounted by the fish-eating bug, 

 Belostoma grandis," which was in the act of killing the fish by 

 piercing its head ; and Todd, the same year, describes how a 

 Belostoma, about three-quarters of an inch long, was seen to 

 vanquish a fish three or four times its own length. Uhler, in 

 1884, states that Ranatra destroys the eggs of fishes, and some- 

 times attacks the young fishes themselves and sucks their blood. 

 Writing of Belostoma grande, the giant species of this genus, 

 that is found in tropical America, he states that, " It is a 

 formidable monster in the pools of Demerara, where it lurks on 



