EGGS AND CATERPILLARS 11 



hold it ; and the second pair of maxillae, which make 

 the " under lip " and are joined in one piece. The first 

 maxillae carry the pal' pi., or feelers. 



When the caterj^illar comes from the egg its head is 

 very large in proportion to its body, but the size of 

 the head does not change until the larva molts, while 

 the body grows so much that often the head looks 

 small in proportion before molting-time comes. The 

 head is stiff with chitin, and when the caterpillar 

 molts, the old head-covering, which is called a mask, 

 is pushed oif in one piece, usually transparent, color- 

 less, and hard as the transparent celluloid which it 

 resembles. Caterpillars' heads are flat, or nearly so, 

 across the front, wider and longer than they are thick, 

 and vary in shape from almost round to the shape of 

 an apple-seed with the pointed end uppermost. 



Among the mouth-parts of the caterpillar opens a 

 little tube called the spinneret. This tube is the outer 

 end of a duct which connects with the silk-glands in 

 the abdomen. When the caterpillar wishes to spin, it 

 forces the gummy fluid secreted by these glands to the 

 mouth of the spinneret, applies it first to some support 

 which shall steady the end of the thread, and then 

 moves its head rather slowly, and the gummy fluid, 

 constantly forced through the spinneret, hardens at 

 once into a silken thread which the caterpillar guides 

 to any point it chooses. As we watch the spinning it 

 looks as if the caterpillar were making lines with its 

 tongue. It is not true, as was stated in one popular 

 book, that "whenever" the caterpillar moves its head 

 from side to side it is spinning. It often moves the 

 head to find another leaf or stem to which it may 



