PRACTICAL ZOOLOGY 39 



Compare the plan of structure of the grasshopper 

 with that of the earthworm, crayfish, and spider. 



Try to get young grasshoppers and note the changes 

 which are shown at the successive molts. 



Butterfly 



Field and Vivarium Study. Note its wavering flight, 

 the way it walks, the position of the wings when at 

 rest, the use of the proboscis when gathering nectar, 

 the species of plants visited, the position of the pro- 

 boscis when not in use. 



Structure. Note the similarity of structure to the 

 grasshopper ; the differences between the wings of the 

 insects ; the greater uniformity in the structure of the legs 

 of the butterfly ; the position of the eyes ; the shape 

 of the antennae ; the structure of the proboscis ; the 

 microscopic appearance of the scales on the surface of 

 the wings (Figs. 70, 71, 221, 238, 241). 



Examine the larva, noting its shape and color ; its mode 

 of locomotion ; locomotor organs ; food and method of 

 feeding (Fig. 73). Put mature larvae (of Mourning Cloak 

 butterfly, for example) in a glass-covered box and watch 

 them as they change to the pupa stage. 



Study the chrysalis and eggs, if obtainable (Fig. 368). 



The bee, fly, and beetle may be used for comparison. 



3. ARACHNIDA 

 Spider 



Field and Vivarium Study. Study the mode of loco- 

 motion; the position, arrangement, and captured con- 

 tents of a web ; the position of the spider in the web. 

 Put a spider into a large pasteboard or wooden box, 

 cover with a sheet of glass, and note how the silk is 

 spun and the web is constructed. Look for cocoons 

 and study their structures and contents. 



