List of Illustrations xi 



14. Nurse Willis Craft sprays a bed at the Arlington, Va. County 

 Hospital with 5% DDT to eliminate the bedbug problem . 78 



15. This soldier is treating the interior surfaces of a barrack 

 with DDT residual spray to insure immunity against mos- 

 quitoes for several weeks 95 



16. A measured quantity of a household spray is atomized into 

 a Peet-Grady chamber in order to determine the effective- 

 ness of the insecticide 96 



17. Flies knocked down during a Peet-Grady test are picked up 

 and counted. They are then transferred to a cage to see 



how many recover within 24 hours 97 



18. This Piper Cub airplane is spraying a DDT formulation over 

 mosquito-infested terrain. This treatment kills mosquitoes 



and larvae as well as adult stages of their life cycle 98 



19. To kill mosquitoe larvae in flowing water, a drip can feed- 

 ing a DDT in oil solution is very convenient 115 



20. A rotary-type hand duster being used to treat a mosquito- 

 breeding place with DDT 116 



21. These Walker-Gordon cows will be more contented after 



the dairy is sprayed with a water suspension of DDT 117 



22. Cows kept free from flies by direct application of DDT will 



give from 3 to 8% more milk than their untreated sisters . 118 



23. This pig will remain free from flies and lice for a long time 

 after her treatment with a 5% DDT dispersion in water . . 135 



24. Cattle on a Florida ranch are sprayed with DDT for control 



of the horn fly 136 



