320 PLANT FRIENDS AND PLANT PESTS 



b. Larva or Caterpillar 



Observations: Note that, besides true jointed legs, the caterpillar has 

 others called prolegs. How many true legs are there and where are 

 they located? How many prolegs are there? Locate the spiracles 

 or breathing holes. Remember where they are located on an adult 

 insect. Watch the caterpillar when it feeds. What kind of mouth 

 parts does it have? Might it do damage to plants? How? * 



Conclusion: i. Is a caterpillar a worm? (Look in a biology for the 

 characteristics of worms.) 2. How might the larvae of moths or 

 butterflies be of economic importance ? 



c. Pupa 



Materials: Cocoons of several species of moths with twigs or other parts 

 attached should be furnished for this exercise. 



Note : Moths spin a cocoon for themselves at this stage. Butter- 

 flies spin no cocoon but form a chrysalis. 



Observations: Where do you find the cocoon or chrysalis? Of what dees 

 the cocoon seem to be composed? (The cocoon of the Cecropia is 

 excellent for this purpose.) In a chrysalis locate by means of the body 

 markings the head, antennae or feelers, eyes, wings, legs, and spiracles. 

 Are all the parts of an adult present ? 



Open a cocoon. What do you find inside ? How do you explain this ? 



Conclusion: Making use of all the knowledge you have gained, write a 

 brief description of the pupal stage of an insect and tell of what use 

 this stage might be to the insect. Remember where you find these 

 stages. 



d. Adult or Imago 



Method: Examine carefully an adult butterfly or moth. 



Observations: How many body regions has it? How many legs? 

 Wings ? Antennae ? How does this stage differ from the pupal stage ? 

 Note : All the changes undergone by an animal from the time it 

 leaves the egg to the time it becomes an adult are known as the 

 metamorphosis of that animal. If no great changes in form occur, 

 the animal is said to have an incomplete or direct metamorphosis. 

 But if changes in form such as in the butterfly or moth occur, the 

 animal is said to pass through a complete or indirect metamorphosis. 



Conclusion: i. What insects that you have studied pass through a direct 

 metamorphosis? An indirect' metamorphosis? 2. If time permits, 

 drawings might be made to illustrate the life history (metamorphosis) 

 of a moth or a butterfly. 



