94 NATURE-STUDY REVIEW [7:4— Apr., 1911 



Grammar Grades 



(Mosquito in either fall or spring; dragon fly in spring) 



Problem 



How may mosquitoes be destroyed? 



Materials 



Tumblers or other glass dishes, mosquito netting, eggs, lar- 

 vae and pupae of mosquito, kerosene, goldfish, tadpole, various 

 water insects. 



Method 



The larvae and pupae should be kept in dishes covered with 

 netting to prevent the escape of the adults. The water stages 

 should be kept till they undergo their transformations, which us- 

 ually takes less than two weeks. When the adults emerge they 

 may be kept in the tumblers and studied. A few larvae and pupae 

 should be kept in separate tumblers so that the time spent in each 

 of these stages may be observed. If pans of water are left out- 

 doors, frequently eggs will be laid on the water. 



Observations 



What must we learn about the mosquito to be able to solve 

 our problem? 



1. The egg. Where are the eggs found? How does their 

 shape enable them to float? Are they laid singly or in 

 masses ? How long before they hatch ? 



2. The larva. As it increases in size, through what changes 

 does it pass? What is its position when at rest? How does it 

 secure air? When disturbed, what does it do? Time one to see 

 how long it remains at the bottom. How many days from the 

 hatching of the egg till the larva goes into the pupal stage ? 



3. The pupa. How does the pupa differ from the larva in 

 position when at rest and in the location and number of breath- 

 ing tubes ? How long does it remain in the pupal state ? How long 

 does it take to develop from the egg to the adult ? 



4. The adult. The male and female differ in appearance. Look 

 at the antennae and palps and determine what the difference is. 

 Place a piece of wood on the water for the insect to rest on. Note 

 the position of the legs and head when resting. Note the number, 

 shape and character of the wings. Describe the mouth parts. If 

 one of these mosquitoes stung you, could it give you malaria? 

 Explain. Find out what you can about the relation of mosquitoes 

 to malaria. 



If the common and malarial mosquito can both be obtained, 



