346 GENERAL BIOLOGY 



Study 41. External metamorphosis in insects. 



Materials needed: Two selected examples illustrating 

 the two main types of insect metamorphosis, preferably 

 living and actively transforming in the laboratory; i) nymphs 

 and adults of a grasshopper, a mayfly or a stonefly, and 

 2) larvae, pupae, and adults of mosquitoes, or meal-worms or 

 bean weevils, or any other easily managed forms (see 

 appendix). 



Also nymphs and adults of the following in alcohol: 

 grasshoppers, (Orthoptera) ; psocids, (Corrodentia) ; stone- 

 flies, (Plecoptera) ; mayflies, (Ephemerida) ; dragonflies, 

 (Odonata) ; bugs, (Hemiptera) : and larvae and adults of 

 any Neuroptera, Trichoptera or Mecoptera, of Lepidoptera, 

 of Coleoptera (a weevil, and a larva with legs) , of Hymenop- 

 tera (a sawfly and a bee or ant) and of Diptera, (mosquito 

 or cranefly or other nematocerous larva, and one of the 

 degenerate housefly or fleshfly type). 



Prepare a table with the following column headings, 

 abbreviated as desired : 



1. Name of insect. 



2. Order to which it belongs. 



3. Relative size of head, thorax and abdomen, 

 expressed in the ratio i :x:y. 



4. Skin (thick or thin, hairy spiny or naked, etc.) 



5. Eyes (well- or ill-developed, large or small). 



6. Antennae (relative development) . 



7. Mouth parts (adapted for biting or sucking, or 

 vestigial) . 



8. Wings (externally or internally developing). 



9. Legs (relative development). 



10. Peculiar parts (parts found in this larva only). 



11. Lives where. 



12. Eats what. 



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