Field experiments carried out in 1945 at Rosh Pina in Palestine have proved the great efficiency of DDT residual spray in houses against sandflies.

A high degree of protection against P. papatasii, P. major and P. chinensis was obtained by inside spraying of rooms with DDT in kerosene.

The residual action lasted for 52–58 days during the hot summer months. At the end of this period the effect was still undiminished but the end of the sandfly season made further observations impossible. Judging from observations made elsewhere it may be assumed that the residual effect would have lasted not more than another two weeks.

Dosage of 1 g. per m2 (100 mg. DDT per sq. ft.) was fully effective, and 2 g. per m2 gave no better results. The best method of application is the treatment of all internal surfaces (walls and ceiling). As sandflies tend to congregate in the angle between wall and ceiling, treatment of walls and this angle only gives equally good results.

An attempt to protect a house by spraying “barriers” (vertical surfaces of stone walls etc., within a radius of 50 metres) failed. Sandflies on the outside surfaces disappeared after the DDT treatment but the observations recorded here and those reported by other authors suggest that much larger areas would have to be sprayed in order to make this method effective.

A marked reduction of sandflies in untreated rooms followed the spraying of other Tooms in the same house with DDT. The mechanism of this phenomenon is explained. A general reduction of the sandfly population can be expected when large-scale DDT treatment is carried out in a village or camp area.