THE LIFE HISTORY OF INSECTS 301 



time. Low temperatures are not injurious, but too much moisture must be 

 avoided. The latter part of March the pupae may be brought out and again 

 placed under observation.) 



Exercise 57. The emergence of the adult. Note the date and the method 

 of emergence, and write a brief description of the adult. 



SECTION XX. COMPLETE METAMORPHOSIS. LIFE HISTORY OF 

 THE FRUIT-FLY (DROSOPHILA SP.) 



Material. Material for this work may be secured by placing decaying 

 bananas in the sunlight for a few days. The material should then be cov- 

 ered with a bell jar and used as a stock culture. Each student should be pro- 

 vided with a glass tumbler containing about one fourth of an inch of decayed 

 banana. Cut a piece of black paper the size of the tumbler and lay on top of 

 the banana, and cover the tumbler securely with a glass plate. The student 

 should then place three or four adult fruit-flies in the tumbler. 



Exercise 58. Write up a careful set of notes on the following points : 



1. Describe, and make a drawing of egg, which will be deposited on the 

 black paper. 



2. Note the length of time of incubation. 



3. Describe, and make a drawing of a larva. 



4. If possible, determine the length of the larval stage. 



5. Describe, and make a drawing of a pupa. 



6. Determine the length of the pupal stage. 



7. Describe the adult, and determine the distinguishing characters of the 

 sexes. 



