3. Gradual Metamorphosis. — In this type of development the changes 

 are gradual (Fig. 206) and the egg develops into a young nymph which 

 resembles the adult in general body form and lives in the same general 

 kind of environment as the adult. There is a gradual growth of the body, 

 wings, and appendages. Briefly, the stages are egg, nymph (air breath- 

 ing), adult (air breathing), egg. 



4. Complete Metamorphosis. — In this type the egg hatches into a 

 "wormlike" larva (lar' va) (L. larva, mask) which changes into a quies- 

 cent pupa (pu'pa) (L. pupa, baby), and the latter in turn develops into 

 an adult (Fig. 207). The larva bears almost no resemblance in form 

 to the adult. Commonly, the larvae of the Coleoptera are known as 

 grubs, those of the Diptera as maggots, and those of the Lepidoptera as 

 caterpillars. Even though the pupa stage is usually nonmotile, internally 

 great changes occur. For example, the larva enters to become the pupa, 

 but an entirely different adult emerges from the pupa. Great structural 

 and physiologic changes take place in this so-called "inactive" pupa. At 

 the same time, the pupa always "knows" the specific kind of adult it is 

 to produce. The markings on adults of certain species are so accurately 

 formed that they are used in classification and identification. In com- 

 plete metamorphosis, the stages are egg, larva, pupa, adult, egg. 



QUESTIONS AND TOPICS 



1. What are the principal points used in the classification of insects into orders? 



2. Learn the exact spelHng, correct pronunciation, derivation and examples of 

 each order of insects. 



3. From a study of the table and typical, representative insects, describe each of 

 the following: mouth parts, types of metamorphosis, number and structure 

 of wings. 



4. Describe each of the types of metamorphosis in detail with examples of each. 



5. How can we differentiate between the biting bird lice {Mallophaga) and the 

 true lice (Anoplura) ? 



6. How can we differentiate between fleas (Siphonaptera) and lice? 



7. How can we differentiate between termites (Isoptera) and true ants (Hyme- 

 noptera) ? 



8. Do all insects have the same type of mouth part in the embryo and adult 

 stages? Give specific examples to prove this point. 



9. How many pairs of legs do all adult insects possess? How many antennae? 



10. Why are insects classified as arthropods? 



1 1. What is the method of respiration of adult insects? 



12. How can we differentiate in general between moths and butterflies? 



13. List all the benefits which you have derived from such a study of insects. 



SELECTED REFERENCES 



Brues and Melander: Classification of Insects, Harvard University Press. 

 Chu: How to Know the Immature Insects, William C. Brown Co. 

 Comstock: An Introduction to Entomology, Comstock Publishing Co., Inc. 



