D.D.T. AND FLIES

Greymouth Evening Star, 23 November 1945, Page 3

D.D.T. AND FLIES

DEPARTMENT’S STATEMENT. | WELLINGTON, November 23. Frequent complaints about the ef- I fectiveness of D.D.T. have been re- Il ceived by the Health Department, I but they ah arise from over-optim- I ism. An official statement by the i Department states the Department has been blamed for making regulations restricting the strength of D.D.T., and the merchants who sell it have been criticised for exploiting the public by selling it in concentrations that are too low and therefore ineffective. The statement continues: Actually none of this is true. The Department has made no regulations fixing the strength and has no-powers 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 one or two per cent, in kerosene. Had D.D.T. been offered for sale in concentrations of five per cent, or more it would have been more dangerous to handle, and it is probable there would have been the same complaints, as these arose from over-op-timism combined with failure to realise the supreme importance of 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. The fly poisoned with D.D.T. may take one or two hours to die. It has no knock-out effect like pyrethrum, so that spraying the solution in the air of a room is largely applying the solution to 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 flies which alight on these will absorb sufficient of the poison to' be killed eventually, but not immediately. For this purpose one or two per cent, solution is quite effective, and the only difference about the stronger solution would be that the 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 the fly larvae. “It is certain the fly nuisance will never be ended unless effective steps are taken to prevent fly breeding,” the statement concludes.