340 



ELEMENTARY ENTOMOLOGY 



of using this is to fit a cyanide or alcohol bottle over the lower 

 end of the funnel, and sink the bottle and funnel in the ground 

 level with the surface. This is particularly useful along the coast 

 or in sandy localities where ground beetles are numerous. This will 

 prove more effective for carrion beetles if a dead fish, mouse, or 

 piece of meat is strung on a wire and laid across the funnel. The 

 funnel is also used in collecting very small insects, like Thysanura. 

 The simplest method is to take an ordinary glass funnel, from 

 twelve to twenty-four inches in diameter, and place a cork stopper 

 in the lower end of the neck. The neck is 

 to be partly filled with alcohol. The funnel 

 should then be placed in a basin with 

 straight sides, which is partly filled with 

 water. The basin may be of tin or granite 

 ware, of slightly smaller diameter than 

 the top of the funnel, but deep enough so 

 that the neck of the funnel does not rest 

 on the bottom. If the funnel is not heavy 

 enough to prevent floating, it may be held 

 in position by strips of lead laid across the 

 top. This apparatus should then be placed 

 over a gas flame or some other even heat, 

 and the temperature of the water raised 

 to between sixty and one hundred degrees. 

 Since alcohol evaporates so rapidly, it 

 should not be placed in the funnel until 

 the apparatus is ready for use. The mate- 

 rial containing the insects, such as leaves, 

 decayed wood, etc., is next placed in a sieve, the diameter of which 

 is slightly smaller than that of the funnel. The sieve is then 

 placed over the top of the funnel, and the insects, attracted by the 

 heat, rapidly work their way through the material and drop down 

 into the funnel. The insects are removed from the funnel by taking 

 out the cork stopper and allowing the alcohol to run out into a bottle. 

 A very convenient time to collect these small insects is during the 

 early fall or winter. Cotton-cloth bags may be used to gather up 

 the decaying leaves, wood, etc., which are then brought to the 

 laboratory and the insects sorted out. 



FIG. 476. A simple trap 

 lantern 



