"Our knowledge of the biting habits of _Simulium_ is not complete, but it is evident, as regards American species at least, that these are sometimes not constant for the same species in different localities. Certain species will bite man freely when opportunity offers, while others have never been known to attack him. To assume that the proximity of a _Simulium_-breeding stream necessarily implies that persons in its vicinity must be attacked and bitten is highly fallacious. In Spartanburg County attacks by _Simulium_ seems to be confined to the immediate vicinity of the breeding-places. Our records and observations, exceedingly few in number, refer almost exclusively to such locations. Statements regarding such attacks, secured with much care and discrimination from a large number of persons, including many pellagrins, indicate conclusively that these insects are seldom a pest of man in this county. A certain number of the persons questioned were familiar with the gnats in other localities, but the majority were seemingly ignorant of the existence of such flies with biting habits. This is especially striking, in view of the fact that the average distance of streams from the homes of the pellagra cases studied was about 200 yards, many being at a distance of less than 200 yards, and that 78 per cent of these streams were found to be infested by larval _Simulium_. Such ignorance in a large number of persons cannot be overlooked and indicates strongly that our belief in the negligible character of local attacks by _Simulium_ is well founded." "In localities infested by 'sand-flies,' mosquitoes, etc., these pests are always well known and the ignorance described above is very significant." "Such positive reports as we received nearly always referred to bites received in the open, along streams, etc., and observations made of their attack were of those on field laborers in similar situations. Males engaged in agricultural pursuits are almost exempt from pellagra in Spartanburg County. During the season of 1913, in some two or three instances, observations were made of the biting of _Simulium_ and some additional and entirely creditable reports were received. These observations and reports were under conditions identical with those referred to in the reports of 1912 and confirm the conclusions based on the observations of that year. I would repeat with emphasis that it is inconceivable that a fly of the appearance and habits of the prevalent species of _Simulium_ could be present in such a region, especially about the haunts of man and attack him with sufficient frequency and regularity to satisfactorily account for so active and prevalent a disease as pellagra without being a well-known and recognized pest." "In connection with the conditions in the Piedmont region of South Carolina, it may be well to cite the results of a study of those in the arid region of western Texas."