Flowers, herbs, and boughs should be swept with a sidewise motion. A sidewise sweep will collect more insects than an upward or downward sweep and at the same time mutilate less. If care is taken not to damage flowers or foliage, the same patch of plants may be visited several times with profit. The contents of the bag should be removed after every few sweeps or strokes. This practice will prevent damage to the insects caused by being jostled about in the net with a large amount of debris.
Killing Bottles
The best killing agents for use in bottles are either potassium cyanide or calcium cyanide. These compounds give a concentration of deadly fumes sufficient to kill most insects in a very short time, which is desirable. Generally, two sizes of bottles are used, and in either of them one of these cyanides may give good results. Only a small supply should be purchased at a time, as they deteriorate rapidly.
Construction.—A pyrex glass test tube or strong ring-necked vial, about three-quarters inch wide and 4 to 6 inches long, makes a good cyanide bottle of the smaller size, [fig. 3]. Put about three-quarters inch of granular potassium cyanide or calcium cyanide flakes in the tube or vial. Cover with a tight plug of cellucotton, on top of which put one or two loose plugs. Instead of cellucotton, you may use sawdust and a plaster of Paris batter. In the latter case, cover the cyanide with one-quarter inch of sawdust and over it pour one-quarter inch of newly mixed, thick batter of plaster of Paris and water. Allow the batter to harden for a few hours; then keep the bottle tightly corked except when it is being used.
Fig. 3.—Cyanide killing bottles. The lethal chemical, 1, is potassium cyanide or calcium cyanide and is covered with a layer of cellucotton, 2, or sawdust, 3, and plaster of Paris, 4. The rest of the bottle is filled with soft, loosely crumpled, lint-free paper, which should be changed whenever it gets damp. The bottles should be tightly corked and labeled POISON. The collector should not test their strength by smelling.
The larger cyanide bottle, [fig. 3], which should be sturdy, may range in capacity from one-half pint to a quart. In the larger bottle, the cyanide should always have the plaster of Paris covering. The layer of sawdust and plaster should be a little thicker than that for the smaller bottle.
Care and Use.—Label all killing bottles and other containers of cyanide conspicuously with the word POISON; keep them tightly corked and away from children or adults who do not realize the extreme deadliness of the compounds. Never test the strength of a killing bottle by taking the cork out and smelling the contents. As an added precaution and safeguard to the collector, tape the bottom of the cyanide bottle to protect it against breakage.
The bottle should be almost entirely filled with loosely crumpled, soft paper, which should be changed whenever it gets damp. This paper will help keep the specimens from rubbing against each other inside the bottle and thereby being damaged.
Each collector should have several cyanide bottles and follow carefully these practices.