i.i U.KTIN OF THE WMIT.I) STATES PISH COMMISSION '271) 



the surface of the water ; the head is benl downward and the rospira 

 tory tube, surrounded i>.\ very fine cilia, points upward liken Anger. It 

 one reaches for them, or slightly agitates the surface of the water, they 



go rapidly toward the bottom with quick, eel-like wriggles, to rise again 

 in a similar manner after a short time. 



After the skin has changed for the last time the larva becomes a 

 chrysalis. The larva and chrysalis arc as different from each other as 

 the chrysalis of a butterfly from a caterpillar, But while the chrysalis 

 of a caterpillar remains immovable, the chrysalis of the Culex, when in 

 the water, is hardly less lively than its larva ;. and it is, therefore, not 

 astonishing that it has sometimes been taken for a separate aquatic an 

 imal. It differs from the larva by its form and the manner in which it 

 carries itself. When quietly resting on the surface of the water it has 

 its thick, plump head turned upward; from the head two respiratory, 

 tubes protrude above the surface like two little pointed ears, while the 

 larva has only one respiratory tube, which is somewhat longer and starts 

 from the back part of the body. After eight or ten days the Culex slips 

 out of the chrysalis, and the empty chrysalis shells may then frequently 

 be seen floating on the water. 



Every female Culex lays, on an average, 300 eggs, and after that it 

 dies. The development from the egg to the larva, chrysalis, and the 

 youug winged insect is completed in four or five weeks. From spring 

 till autumn about six generations may, therefore, follow each other, in 

 enormously growing proportion ; and the vast number of these insects 

 will no longer seem astonishing, their cradle being the water. Tin; 

 water, however, is not only the cradle of thousauds and millions of these 

 insects, but it also becomes the early grave of a great many of them; 

 for other animals living in the water, particularly fish, devour every day 

 enormous numbers of these larvae. 



In what manner may "the larva? of the Culex be obtained, so as to form 

 the food of artificially hatched young fish ? The answer will not be 

 difficult after all that has been said. In the beginning of spring sonic 

 open receptacle for water, such as an old barrel or tub, is placed some- 

 where in the open air and filled with water, to which it will be well to 

 add some pond-mud, leaves, decaying straw and perhaps cow-dung, in 

 orther to form a basis for the development of the lower grades of vege- 

 table forms which serve as food for the larva 1 . After a short time the 

 beginning of animal life may be noticed in the water, which should be 

 filled up from time to time, and soon "the barrel will contain thousands 

 of larvse of the Culex. These can be taken out with a gauze dip- 

 per, or they may be obtained in the following manner : A rubber tube, 

 as thick as a little finger and from oO to 80 meters long, serves as a 

 siphon. Iu order to avoid the disagreeable sucking of the tube, which 

 often results in gettiug the mouth full of dirty water, the entire tube is 

 put under the water, the air is allowed to escape, one end of the tube 

 is then pressed together with the thumb and forefinger and is pulled 



