WAR ON FLIES

Manawatu Standard, Volume LXV, Issue 305, 23 November 1945, Page 6

WAR ON FLIES

EFFECTS OF D.D.T. (Press Assn.) WELLINGTON, Nov. 23 Frequent complaints about the ineffectiveness of the insecticide D.D.T. have been received by the Health Department, but they all arise from overoptimism. * An official statement by the department states: The department has been blamed for making the regulations restricting the strength of D.D.T. and merchants who sell it have been criticised for exploiting the public by selling it in concentrations that are too low and, therefore, ineffective. Actually none of this is true. The department has made wo regulations fixing the strength and has no power to do so. The firms who market D.D.T. have co-operated with the department regarding the manner in which it is sold and have carried out the department’s suggestions in" marketing only a dilute solution of 1 or 2 per cent, in kerosene. Had D.D.T. been offered for sale in concentrations of 5 per cent, or more it would have been more dangerous to handle and probably there would have been the same complaints as these which arose from over-optimism, combined -with failure to realise the supreme importance of the natural laws when dealing with insects. “D.D.T. does not kill fly larvae to any effective extent, although it is very deadly against adult flies,” the statement continues. “It is a contact poison and acts rather slowly. A fly poisoned with D.D.T. may take one or two hours to die. It has no knockout effect like pyrethrum, so that spraying a solution in the air of a room is largely applying a solution to the walls, ceilings, electric light cords, and other surfaces where flies are accustomed to settle. When the kerosene evaporates a fine deposit of crystals is left and the flies which alight on these will absorb sufficient of the poison to be killed eventually, but not immediately. For this purpose a 1 or 2 per cent, solution is quite effective, and the only difference about the stronger solution would be that a greater amount of poison would make the supply last longer. “The department warns those using D.D.T. not to rely on the treatment of rooms alone. If fresh flies can come in from refuse heaps where they breed, action should be taken to restrict their breeding, but D.D.T. is not effective for this purpose, as it does not kill fly larvae. It is certain that the fly nuisance will never be ended unless effective, steps are taken to prevent fly breeding,” tho statement concludes.