Insects and Human Health 545 



When mosquitoes infest a room, they may be killed by means 

 of chlorine gas. The room cannot be occupied for many hours 

 afterward because of the noxious fumes. The gas may be pre- 

 pared by putting into a large glass or crockery dish half a tea- 

 cupful of chloride of lime ; pour upon this about one fluid ounce 

 of dilute sulfuric acid. Leave the room immediately and close 

 the door, stopping up larger cracks to prevent the escape of the 

 gas. Care should be taken not to inhale the gas when opening 

 the room later. 



SUMMARY 



A knowledge of the life history and habits of mosquitoes is necessary 

 to the control of certain diseases, such as malaria, transmitted by the 

 Anopheles mosquito, and yellow fever, by the Stegomyia. The Culex, 

 or domestic mosquito, is annoying, but not known to be dangerous. 



The food of the adult mosquito consists mainly of the juices of 

 plants. Only the females suck blood. 



The life history of the mosquito, like that of all winged insects, 

 includes four stages: the egg, larval, pupal, and adult. 



Knowledge of the life history and habits of mosquitoes makes easy 

 their destruction : (1) by draining swamps, (2) by destroying eggs, 

 larvae, and pupae by means of a film of oil. 



Additional protection may be had by the use of screens and certain 

 oils. 



REVIEW QUESTIONS 



1. Why is knowledge of the mosquito important? 2. Where is 

 the Anopheles mosquito found? 3. Give reasons for the selection of 

 the common mosquito for study. 4. Describe the eggs of the Culex, 

 as to appearance, places deposited, number, and time of hatching in 

 usual conditions ; also those of the Anopheles. 



5. Describe the larvae of the Culex as to appearance, locomotion, 

 food, breathing, enemies, and growth; describe the larvae of the 

 Anopheles in the same way. 6. What stage follows the larval stage? 

 Describe. 7. Describe the way in which the adult mosquito emerges 

 from the pupa skin. 8. Give an account of the life of the adult mos- 

 quito, its food and habits. 9. Why do mosquito bites cause swelling? 

 10. Describe the external features of (a) the Culex ; (6) the Anopheles ; 

 (c) the Stegomyia. 11. Of what use is the knowledge of their life 

 history and habits? 12. What measures are employed to prevent 

 the breeding of mosquitoes? 13. How may the adults be kept from 

 attacking us ? 14. How may mosquitoes in a room be killed ? 



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