238 



INSECT LIFE. 



3. Prepare a breeding cage by placing a sod of 

 growing grass in it, put several living male crick- 

 ets in it, and set the cage where the insects can be 

 watched. After the insects have become used to the 

 cage they will chirp, and the pupils can determine 

 how it is done. 



4. Kill a pair of crickets by placing them in a 

 cyanide bottle and then study their wings. How do 



the front wings of 

 the male differ from 

 those of the female? 

 Make drawings 



showing the differ- 

 ences. 



5. If you have 

 the use of a micro- 

 scope observe that 

 the principal vein 

 which extends diag- 

 onally across the 

 base of the fore 

 wing of the male 

 (Fig. 205, a) is furnished' on the lower side of the wing 

 with ridges like those of a file (Fig. 205, b) ; and that 

 on the inner margin of this wing, a short distance 

 toward the base from the end of the principal vein, 

 there is a hardened portion, which may be called the 

 scraper (Fig. 205, c). 



6. Watch a cricket while chirping and determine 

 how the files and scrapers of the two fore wings are 

 used. 



7. Write an account of the way in which crickets 

 chirp. 



Fig. 205, — Musical organs of a male cricket. 



