62 



AN ECONOMIC ENTOMOLOGY. 



until ready for the change to the atlult. Then they crawl up the 

 bteni of some water plant, or upon a projecting stone, and soon 

 the skin splits and the imagos emerge. A few minutes suffice to 

 harden and dry the newly-developed adults, then with spread 

 wings they sail away on a new career, in a new medium. 



In habit the larvae are as predaceous and voracious as the adults, 

 and their prey consists of any aquatic forms which they can cap- 

 ture, — mosquito larvae forming quite a staple article of diet. It 

 jas been already indicated that they are not very active creatures, 

 and prey is captured by simply waiting in the mud or on a mossy 

 stone until it comes within reach. Their color renders them 

 almost in\ isible under such conditions, and nature has furnished 

 a remarkably extensile mouth structure, by means of winch they 

 are able to reach out some distance and seize whatever creature 

 may be passing near. It is the labium, or lower lip, that is 

 modified for this plirpose, and is supplied with a double hinge 

 which can be straightened out rapidly to bring into play a pair of 

 large, slender, and pointed jaws at its tip. When this structure is 

 retracted it is invisible, covering the other mouth parts entirely and 

 hiding them. The term "mask" has therefore been applied to it. 

 Oviposition varies with the species, and is interesting. The 

 sexes pair during flight. The male has the organs of copula- 

 tion at the base of the ab- 

 ^^' domen, while the opening 



of the testes is at the tip. 

 Before pairing he fills the 

 seminal pouch at the base 

 of the abdomen, then grasps 

 the female by the neck with 

 a pair of anal claspers, and 

 she curves up the tip of 

 her abdomen into contact 

 witli the opening to the 

 seminal duct of the male. 

 As the eggs are fertilized 

 the pair descend to the 

 surface of the water, the 

 female drops a little mass upon the surface, and copulation is 

 resumed, the process being repeated until all the eggs are laid. 



•species of W^>-/ore and its larva ; the latter witli 

 anal gill-tufts. 



