COLLECTING AND PRESERVING INSECTS- — BANKS. 83 



Sweeping. — The use of the beating net continues profitable from 

 spring till fall, a different set of species appearing with each season. 

 Low and swampy meadows, meadows on the slopes of mountains 

 or surrounded by woods, low underbrush, and herbage in smaller 

 patches of woods, are very good beating grounds. Dry and sandy 

 meadows are less productive, but harbor usually a different set of 

 species on account of the difference in the flora. Pastures and mead- 

 ows much frequented by cattle and horses are much less productive, 

 and where a large number of sheep are kept there is usually no chance 

 for using the beating net, since neither grass nor specimens are 

 left. The lawns in our parks and gardens are usually poor collect- 

 ing ground on account of the limited variety of plants in such places; 

 but the few species found there occur in enormous number of speci- 

 mens. The endless stretches of our western prairies swarm at the 

 right season (in June) with numerous Coleoptera (mostly Malachiidae, 

 Chrysomelidse, Mordellida?, Curculionida?, etc.), provided prairie 

 fires have not swept too frequently over the 

 place. Fires and cattle produce a remarkable 

 change in the flora and fauna of the prairies ; 

 many indigenous species disappear or become 

 scarce and are replaced by a much smaller 

 number of imported species. 



Sweeping may commence in the forenoon 

 as soon as the dew has disappeared ; it is less 

 profitable in the heat of midday, but produces 

 the best results late in the afternoon and 

 more especially in the short interval from just 

 before sunset until dark. At this time many 

 rare Pselaphidre and Scydmsenidse, species of FlG - 128 -— A water - beetle. 



Dytiscus. 



the genera Colon and Anisotoma, and other 



small Silphidre, can be beaten from the tips of grasses, all being 

 species which can not, or only accidentally, be found during daytime, 

 when they hide between the roots of plants. 



Collecting on mud and gravel banks. — The mud or gravel banks of 

 rivers, creeks, and stagnant bodies of water are inhabited, especially 

 early in summer, with an astonishing multitude of Coleoptera. 

 Countless specimens of smaller Carabidae (Dyschirius, Clivina, Bem- 

 bidium, Tachys, etc.) and Staphylinidse (Tachyusa, Phdonthus, Acto- 

 bius, Stenus, LatJirobium, Trogophloe.us, and many other genera) will 

 be seen actively running over the mud or sand; many other speci- 

 mens are hiding under the pebbles in company with other species 

 (Cryptolvypnus, Georyssus, etc.) or in little subterranean galleries 

 (Dyschirius, Bledius, Ileterocerus) . All these beetles must be col- 

 lected by picking them up with the fingers, an operation which, owing 

 to the activity of the specimens, requires some little practice. The 

 88552— Bull. 67—09 7 



