Fig. 67.—A Dermestid (Anthrenus scrophulariæ). a, larva, dorsal view; b, larva, ventral view; c, pupa; d, adult—all enlarged.
Sweeping may commence in the forenoon as soon as the dew has disappeared; it is less profitable in the heat of the 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 Pselaphidæ and Scydmænidæ, species of the genera Colon and Anisotoma, and other small Silphidæ 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 Carabidæ (Dyschirius, Clivina, Bembidium, Tachys, etc.) and Staphylinidæ (Tachyusa, Philonthus, Actobius, Stenus, Lathrobium, Trogophlæus and many other genera) will be seen actively running over the mud or sand; many other specimens are hiding under the pebbles in company with other species (Cryptohypnus, Georyssus, etc.) or in little subterranean galleries (Dyschirius, Bledius, Heterocerus). All these beetles must be collected by picking them up with the fingers, an operation which, owing to the activity of the specimens, requires some little practice. The beginner will at first crush or otherwise injure many of the delicate specimens, the capture of which is moreover by no means facilitated by the rapidity with which most of them are able to take wing. The collector must necessarily kneel down and he must not mind getting covered with mud. A good device for driving these species out of their galleries or from their hiding places under stones or in cracks of the ground is to pour water over the banks, and this can in most cases be done with the hand. Larger stones and pieces of wood or bark lying on the bank are favorite hiding places of certain larger Carabidæ (Nebria, Chlænius, Platynus, etc.), and should of course be turned over. Finally, the moss growing on rocks and logs close to the water's edge, and in which, besides other beetles, some rare Staphylinidæ and the Byrrhid genus Limnichus can be found, should be scraped off and investigated on the collecting cloth or on the surface of a flat rock, if such be conveniently at hand.
[Collecting aquatic Beetles.]—The fishing for water beetles in deeper water by means of the water net has already been alluded to (p. [32]), but many species live in shallow brooks with stony or gravelly bottom, where the water net can not be used. The Dytiscidæ and Hydrophilidæ living in such places usually hide under stones, and can in most cases be easily picked up with the hand, or a little tin dipper or a spoon will be found convenient for catching them. The species of the family Parnidæ are found on the underside of rough stones or logs which are either partially or entirely submerged. They are more numerous, however, in the moss or among the roots of other plants that grow in the water. Such plants have to be pulled out and examined over the collecting cloth.
Fig. 68.—A Tiger Beetle
(Cicindela limbata), drawn
by Miss Sullivan—enlarged.
[Collecting at the Seashore and on sandy Places.]—A large number of species belonging to various families live exclusively in the vicinity of the ocean, some on the open beach, others along the inlets, bayous, or salt marshes, and still others on the dry sand dunes. The Cicindelæ are actively running or flying about close to the water's edge and have to be captured with the butterfly net. The remaining maritime species live hidden under the seaweed and other débris cast up by the waves, or in the sand (sometimes quite deep below the surface) beneath the débris or between the roots of the plants growing on the dunes. The majority of the maritime species do not appear before June (in the Middle States), but the collecting remains good until September.
Fig. 69.—The Beaver Parasite
(Platypsyllus castoris),
adult—greatly enlarged.
In dry sandy places away from the seashore, the collecting at the roots of plants is especially to be recommended, and the plants, and more especially the bunches of coarse grasses usually growing in such places, should be pulled up and shaken out over the collecting cloth. This mode of collecting acquires a great importance in the arid regions of the West and Southwest, where, in the warm season, nearly all Coleoptera are hiding during daytime in the ground at the roots of plants.