INTRODUCTORY STUDIES OF LIVING ANIMALS 15 



larva lives, and answer to yourself how its form and color 

 would protect it in those surroundings. 



2. Since the larva is an insect, though immature, its 

 body is composed of three regions : head, thorax, and 

 abdomen. How do these regions differ from each other ? 



3. What structures has your specimen to enable it to 

 move from place to place ? If fully developed wings are 

 not present, what indication is there of their being 

 formed ? 



4. What sense organs has the larva ? Which ones 

 seem to be the largest and. most useful.' 



5. Although the aquatic larva is preparing for adult 

 life in the air, there should be some arrangement for 

 securing air in the water. Where do you find outgrowths 

 of the skin which might increase the air-absorbing surface ? 

 How many of these structures are there .' Look within 

 them for the air tubes, — fine branching black lines. 



6. If possible, without injury to the specimen, examine 

 the larva's mouth. Try to discover how it is used and 

 how it is protected when not in use. 



Suggested drawings. 



a. The entire larva, X 4. 



b. A gill, as seen through the microscope. 



c. The feeding apparatus, x 10. 



PLANT LICE AND SCALE BUGS 



Plant Lice (Aphids) 

 Materials. 



Plant lice on various kinds of plants, such as house 

 plants, golden glow, and other plants from the garden or 

 field. Garden asters with root lice (the asters should be 

 transplanted into pots). 



