Phlebotomus papatasii is a small midge measuring about 3mm. in length, of a very delicate build and thickly covered with fine, long hairs. The body is of a pale lemon tint and shows the mor phological characters common to its genus. Eyes are relatively large, black and conspicuous. The antennae are long and fila mentous. The proboscis is long and prominent. The fine wings are lancet-shaped, covered with hairs and held erect, except when newly hatched and shortly before death. The female fly has a spindle-shaped abdomen.
The life-history of this fly covers a period of about eight weeks, the exact time depending on food supply, temperature and humidity. The egg stage occupies about 9 days; the grub stage about 28 days; and the chrysalis stage about so days, ending in the emergence of the adult fly. The wings of the newly hatched fly are crumpled and moist. Until these are dry the young fly can only crawl. The recognition of this stage is most helpful in detecting breeding spots of the insect. During the night, when the atmospheric humidity is usually great, the wings cannot dry. The process of drying is usually completed within three hours after dawn, and the mouth parts are sufficiently hardened to allow of the sucking of blood during the first 24 hours of adult life. Copulation can take place within the next 24 hours, and eggs to the number of 4o are laid 6 to so days later. The length of life of the adult female fly in nature is about two weeks, though in the laboratory life may be prolonged for 3o days.
it avoids all currents of air, natural or artificial. Upstair rooms, which are more exposed to air currents, are less infected than those on the ground-floor. In nature the grub and chrysalis forms are found in the cracks in embankments, in the loose earth at the base of walls and buildings, in cultivated soil and in other places where suitable conditions of food, moisture and tem perature exist. The grubs are found even to a depth of a foot or more in loose soil, and can migrate to the level of optimum en vironment. Hibernation takes place in the last grub stage, a very resistant stage. When ready to pass into the chrysalis form, they seek a drier spot, usually within a few inches of the surface of the ground. Excess of moisture is injurious to all stages of the life of this insect.
About 8o% of newcomers to sandfly regions suffer from the fever during their first summer of residence, and about 15% develop a second attack within three years. Such factors as atmos pheric temperature and humidity affect the development of the virus in man.
Prevention.—It is necessary to eliminate the hiding and breeding places of the fly. Cracks in the ground or in masonry must be got rid of by levelling, pointing, etc. Premises must be thoroughly cleansed, and dust and cobwebs removed. Good refuse disposal is essential. The sandfly must be kept away by sandfly proof nets (45 meshes to the square inch), electric fans or repellants, such as paraffin or camphor; whilst insects living in corners of rooms must be destroyed by swatting with a damp cloth or spraying with 1 % cresol. There must be a daily war against this pest. All the necessary repairs, tarring, painting and lime-washing must be carried out immediately before the warm weather sets in. Each year the interior of all rooms should be washed down and painted or lime-washed.