OTHER ENEMIES OF MAN 



221 



TOPIC 2. OTHER ENEMIES OF MAN 



SUGGESTED PROBLEMS AND QUESTIONS 



1. Why is the house fly a deadly enemy of man? 



2. What is the life history of the house fly? 



3. How can we protect ourselves from flies? 



4. What is the life history of mosquitoes? 



5. How can we control mosquitoes? 



6. Why is the rat often spoken of as the "na- 

 tional pest"? 



7. How is plant life affected by insect pests? 



8. How are insect pests controlled? 



SUGGESTIONS AND HELPS FOR STUDY 



1. Insects are important as carriers of disease 

 germs. Files and mosquitoes are the worst offenders 

 in this respect. Be sure to make a careful study of 

 these two forms. 



2. Read several references on the questions and 

 problems in this topic. 



3. The scientific control of animal pests depends 

 upon our knowledge of their life histories and their 

 breeding places. Outline this information for each 

 of the pests mentioned in the problems. 



4. Study the meanings of the following words : 



genus any microscopic plant or animal organisms 



that cause diseases. 

 regurgitate to pour back again. The fly pours partly 



digested food from the stomach back into the 



mouth. 



EXPERIMENTS OR DEMONSTRATIONS WHICH WILL 

 HELP ANSWER THE PROBLEM QUESTIONS 1 



Activity 137. What are some common animal pests? 

 How can we combat them? 



Among the animal enemies of mankind are the fly, mos- 

 quito, clothes moth larva, bedbug, rat, mouse, louse, and 

 cockroach. In your notebook, state how each of these is a 

 pest and how it may be combated. 



Experiment 138. What is the life history of flies? 



Place some fresh meat in a glass jar where flies may feed 

 upon it. Examine it for fly eggs, and after you have found 

 some, cover the jar with mosquito netting. Watch their 

 development into adult flies and keep a record of the stages 

 through which they pass. Also keep a record of the time. 



In your notebook record your findings and answer the 

 following questions. What are the four stages in the life 

 history of a fly? Where does the house fly usually lay its 

 eggs? What is the larva of a house fly called? 



Experiment 139. What is the life history of mosqui- 

 toes? 



Place a can of water under some bushes or in high grass 

 where mosquitoes are known to be. Mosquitoes lay their 



1 See workbook, p. 80. 



eggs on stagnant water. Bring the can into the classroom 

 and cover it with mosquito netting. Observe the develop- 

 ments which take place. 



Put some mosquito larvae in another jar or can (the 

 larvae usually can be found in rain barrels, old cans with 

 water in them, or water puddles). Add some kerosene to 

 the water. 



Put a goldfish or a minnow into a jar containing mos- 

 quito larvae. 



In your notebook record your findings and answer the 

 following questions. What are the four stages in the life 

 history of mosquitoes? Where do mosquitoes lay their eggs? 

 How may mosquitoes be combated? Do mosquitoes in your 

 locality carry disease germs? 



OTHER INVESTIGATIONS WHICH YOU CAN MAKE 



1. Make a survey of your home and collect specimens of 

 all insects you see. Determine whether these insects are 

 harmful or useful. 



2. Make a survey of your community and find all the 

 places where flies and mosquitoes may breed. Report your 

 results to the class and suggest ways of remedying the 

 situation. 



3. Make a special investigation of animal pests that de- 

 stroy food and clothing. 



READINGS WHICH WILL HELP ANSWER THE 

 PROBLEM QUESTIONS 



More than seven hundred thousand different kinds 

 of animals inhabit the earth. All are adapted to their 

 surroundings; otherwise they could not live. They 

 have needs similar to ours although often the methods 



U.S.Pueuc HEALTH SERVICE 



Bureau of Public Health Service 



FIG. 350. REGURGITATION OF FOOD BY A HOUSE FLY 



of satisfying them may be different. Man dominates 

 all other forms of life, but his supremacy is not main- 

 tained without a struggle. In some parts of the earth 

 people still live in fear of lions, tigers, and huge 

 snakes. In our own country, we are no longer forced 

 to match our skill with the cunning of wild beasts, 

 but we are constantly at war with insects and other 

 animal pests that destroy our food supply and spread 

 deadly diseases. There is scarcely a crop of any kind 



