Insecticidal Effect of Surface Deposits of D.D.T. on Mud

Abstract

Observations in the field^1,2 have shown that mosquitoes become affected after making contact with D.D.T.-treated surfaces in rooms and may make their escape through open doors and windows. Kennedy³ has shown in the laboratory that sub-lethal doses of D.D.T. excite mosquitoes, and that when activated they move preferentially to light. For residual spraying in houses to be successful in reducing the incidence of malaria, it is essential, therefore, that the surface deposit applied shall be lethal to mosquitoes after only a brief contact.