260 rEESH-WATEE AQUAEIA. 



of the plant upon wMch they are hatched, and then after a 

 time proceed to make for themselTes a case or home out of 

 its leaves. The case is usually made of two pieces of leaves 

 neatly joined together. The larvae of some of the Sydro- 

 eampidce use more than two portions of a leaf in the con- 

 struction of their cases. For instance, the larvse of the 

 Caiaclysta lemnalis, as its specific name inaplies, feeds upon 

 duckweed, and of several of the leaves of this plant it makes 

 its home or case. The larvae of the " China Marks," as they 

 grow, from time to time enlarge their cases, or, as the leaves 

 forming them decay, repair them. They enter and complete 

 their pupalhood while in their larval homes. These creatures 

 are herbivorous, and feed generally upon the leaves of the 

 plants on which they are born, and of which they make their 

 cases. They do not always, however, confine themselves to the 

 same weed either for food or for building material. One of 

 the most beautiful of these " CMna Marks " is the Hydro- 

 cairvpa stagnalis, and its larva is suitable for the aquarium. 

 The vessels in. which these larvse are confined should be pro- 

 vided with plenty of water-weed — such, for instance, as the 

 Vernal Starwort {Gallitriche verna), (Fig. 50), which ought to 

 be placed in the tank aocordiug to directions given on p. 70. 

 There are many people, I believe, who look upon Gnats and 

 their near relatives the mosquitoes as not only tormenting, 

 but useless and uninteresting, insects; whereas, in fact, at 

 least during the greater portion of their lives, they are 

 both useful and very interesting. And to look upon aU Gnats 

 as tormentors is to err not a little in the matter of justice; 

 for it is only the female members of the family which are 

 guilty of what is commonly called "biting." The males are 

 known by their plumed or feather-like antennse, which have 

 been compared to ostrich feathers on a very minute scale. 

 The females are also plumed, but in a small degree when 

 compared with the males, and there is no difficulty in distin- 

 guishing the sexes. Sometimes, during fine weather, Gnats 

 are seen fiying together in such multitudes that at a distance 

 they look like columns of smoke. It is only, as a rule, the 

 males which thus assemble in the air. For food, Gnats 



