Preliminary Experiments With Sodium Fluoride and Other Insecticides Against Biting and Sucking Lice

rested regions to concentrating points from which they were transshipped to Europe for military purposes may have resulted in the establishment of other loci of infestation not now known. Increased activity at this time in the shipment of horses from the infested territory for use in our own cavalry and for agricultural purposes will no doubt give every opportunity for the insect to become widely established if some natural agencies do not prevent or steps are not taken to destroy the bots before horses are shipped. The accompanying map shows the probable present distribution of the species in the United States, and indicates the points where its presence has been observed by us or recorded by correspondents. The comparatively small number of large dots in North Dakota is explained by fewer circulars being sent there rather than by a smaller number of nose flies.