LIFE HISTORY OF THE MOSQUITO 71 



must provide a dish of water, which may be sweetened with 

 sugar. 



H. Several days must elapse before the fly is sexually mature, 

 when copulation occurs, and the females shortly thereafter de- 

 posit eggs. 



I. Data on the length of life of any animal is valuable, so that 

 the student should endeavor to keep the flies alive as long as 

 possible, noting the time of death. 



J. Flies as carriers of bacteria. 



a. Collect half a dozen houseflies out of doors, noting the 

 immediate environment and sex of the individuals. The flies 

 must be collected in sterile vials. 



b. Prepare six sterile agar plates. 



c. Place the agar plates under sterile bell-jars and liberate 

 one fly for each plate and wait until the flies have crawled about 

 on the agar. 



d. Note the condition of the agar. Can you see any tracks 

 that the flies have made? 



e. Place the agar plates in a bacteriological incubator and 

 incubate for 36 hours. 



f. What changes have taken place, and what are your con- 

 clusions? 



EXERCISE 40 



LIFE HISTORY OF THE MOSQUITO 



A. Collect several egg rafts of a common Culicine mosquito. 

 There are usually pools of standing water, or nearby horse- 

 troughs, on the surface of which the egg rafts can easily be seen. 

 Count the number of eggs in one of the rafts. 



B. Place the eggs in a pint fruit jar, partly filled with water 

 taken from the original pool. 



C. Note the date when the larvae (wrigglers) emerge. 



D. Change the water in the jar from time to time by drawing 



