INSECTICIDES AND REPELLENTS 



43 



Figure 14. — Applying a residual spray with a wheelbarrow sprayer. 



Dispersal Equipment 



Sprayers. — The first airplane spray equipment developed and tested 

 with DDT solutions was designed for use on an L-4 (Piper Cub) 

 airplane. In this model, known as the Husman-Longcoy spray unit, 

 the insecticide was dispersed through six nozzles mounted on the 

 trailing edge of a venturi suspended beneath the fuselage. Soon after- 

 ward an underwing spray boom was developed and used both on 

 monoplanes of the L-4 type and on biplanes of the PT-17 (N2S 

 Stearman) type (fig. 15). Openings of a suitable size for dispersal 



Figure 15. — A PT-17 plane equipped with underwing spray booms. 



