WELCH] WATER IXSECTS 223 



turbed. Xone are likely to be found in an active state. Most 

 torpid specimens when brought into a warm temperature liven up 

 and in time become -quite active. 



Economic Importance of the Common Water Insects. 



The fact that aquatic insects are related directly or indirect- 

 ly to human welfare is usually overlooked or at least underesti- 

 mated. Aquatic insects'' may be of economic importance in one or 

 both of two ways: (1) they may be hurtful, or (2) they may be 

 beneficial. A brief statement of a few of the well 'established 

 facts will indicate the nature of these effects. 



(1). Detrimental Water Insects. — It is now definitely 

 known that, aside from the annoyance of its bite, the adult mos- 

 quito is of vital importance to man because of the part it plays 

 in the carriage and transmission of Malaria and Yellow Fever. 

 Black Flies torment domestic animals and are a serious annoy- 

 ance to man. The Larger Giant Water Bugs, the smaller Giant 

 Water Bugs, the Diving Beetles (both larvae and adults), the 

 Water Scorpions, and the Backswimmers are all said to attack 

 young fish and to be a menace to fish culture. 



(2). Beneficial Water Insects. — The Water Scorpion ren- 

 ders service in preying upon larval Mosquitoes while the adult 

 Dragon Flies are said to make war upon the adult Mosquito. 

 Water insects are of special economic importance in that they 

 constitute such a large percentage of the food of our commer- 

 cially valuable fishes and are thus one of the important factors 

 in the fish industry. 



The Making of a Permanent Collection of Insects. 



The writer is one of those who believe that in the making of 

 an insect collection there is much to be gained for the beginner, 

 particularly if the collecting be properly guided and controlled. 

 Two rules may be established for general procedure : 



(1). Learn all you can concerning the insect and its ac- 

 tivities while it is alive and in its native haunt. When this is 

 completed as far as possible or practicable, then — 



{'2). Secure a moderate number of specimens for a collec- 

 tion. 



In general, it will be desirable to use the following methods 

 for preparing aquatic insects for a collection: (1) Adult insects 

 can be pinned and allowed to dry. or if so desired, can be pre- 

 served in alcohol or formalin. (2) Larvae and Xymphs will 

 need to be put into some preserving fluid: pinning is not to be 

 recommended since drying produces distortion. 



