216 The Philippine Journal of Science 1913 



longevity of these proved to be ten days, and the maximum 

 eighteen days. Captive flies were used in the first experiment 

 and laboratory-bred flies in the second. 



In considering the feeding habits of the female, it is deemed 

 profitable to discuss the notes taken from observations made at 

 close range with laboratory-bred flies fed on experimental ani- 

 mals. The behavior of flies bred in the laboratory indicates that 

 the female does not feed on the day of its emergence. Thirty 

 individuals tested in this regard refused to feed on the first day 

 of emergence, 3 fed upon the second day, and the remainder took 

 the initial feed upon the third and fourth days. 



The insertion of the proboscis seems to be not the only means 

 of obtaining blood, for, when abrasions of the skin of the animal 

 exist, the fly may actually fill itself to the engorging point by 

 means of its spongy labellum. In this process the latter organ 

 is unassisted by the other mouth parts. The proboscis is a dis- 

 tinct appendage never cooperating with the lapping organ. The 

 labellum is situated posterior to the piercing structures ; it is held 

 in this relation either when at rest or when active. When the 

 labellum is in action, the stomal disks which constitute the lapping 

 structure are unfolded downward and outward, bringing the 

 pseudotrachea of the lapping area in contact with the moist 

 surface of the skin. The female laps the blood offered in the 

 same manner as it would any desirable liquid. This does not 

 appear to be a usual method of obtaining blood, since it has 

 never been observed under natural conditions. If it did occur 

 in nature it is obvious that it might prove of importance in 

 the mechanical transmission of animal diseases. This is at 

 once apparent when one considers the area of the exposed sur- 

 face of the lapping organ of this fly as compared with that of 

 other flies infesting domestic animals. 



Under experimental conditions Tabanus striatus bites usually 

 not oftener than once in two days. A few instances have been 

 noted of biting on consecutive days, but this is considered 

 abnormal. 



The process of inserting the various elements of the proboscis 

 is difficult to ascertain since the large head conceals the biting 

 parts when the vertex is lowered. In the process there are 

 no movements which might be considered as premonitory. The 

 fly when applied to the host quickly lowers its head, braces 

 itself on its widely spread legs, and stabs its victim. The end 

 of the abdomen is scarcely inclined, but settles in position parallel 



