THi; COMMOX MOSQUITOES OF MINNESOTA 75 



injure the specimen. ]\Iost mosquitoes are too small for a service- 

 able insect pin to be used in pinning. It is best to use small blocks 

 of pith or cork, about twice as long as wide. Through one end 

 thrust an extremely hne pin, known as a "minutien pin," and impale 

 the mosquito either thruugli the thorax from front to back or from 

 side to side. Through the other end of the block force a large 

 insect pin. The cork should project to the left of this large pin and 

 the mosquito should ha\-e the head forward and legs projecting 

 toward the left. On the large pin place a small label, bearing the 

 place and date of collection and other important information desired. 

 The specimens can then be stored in a cork-lined, tight-titting insect 

 box. 



Minnesota mosquitoes may be grouped roughly into (1) those 

 which breed in artificial collections of water in the vicinity of human 

 habitations or those which we may call domestic mosquitoes, and 

 (2) those which breed in natural collections of water either perma- 

 nent or temporary, open or in woodlands. These restrictions are 

 not entirely binding, for the domestic mosquitoes may, under stress 

 of circumstances, breed in swamps and the second group occasionally 

 in artificial collections of water. The former group includes Citlcx 

 pipicns and Culcx rcstitans. The rest of our mosquitoes belong to the 

 second group. 



\\ e have several of the peculiar northern forms which produce 

 only one generation in the spring, and whose eggs lie over winter 

 at the bottom of swamps or in wet or damp places where snow water 

 will collect the following spring, providing a suital)le medium for 

 the growth of the larvae. These large spring broods may fly con- 

 siderable distances from their breeding places. These facts make 

 the control of our mosquito pest a peculiarly difficult one. 



In cities control measures must be directed first against the 

 domestic forms. This means prevention of breeding in rain barrels, 

 rubbish heaps, sewer catch basins, roof drains and any other place 

 where water may collect and remain for a couple of weeks. This 

 can be accomplished bv covering the water receptacles with netting 

 or oil, or by cleaning up rubbish heaps so that old tins will not hold 

 water, placing oil in sewer openings, keeping roof drains cleaned 

 out, etc. Measures against the swamp-breeding forms must be car- 

 ried out at the same time, must extend well afield and must be 

 carried out at the proper time to reach the early spring breeding 

 forms as well as the late forms. W'here marshes cannot be filled 

 or drained, they must be sprayed with kerosene or petroleum oil 

 at frequent intervals. The first spraying must be carried out early 



