118 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 6 



knee. This is the situation usually chosen by the fly in feeding on 

 bovine hosts, apparently on account of the relative freedom from at- 

 tack by the tail or mouth of the host and the comparative shortness 

 of the hair which permits of easy penetration. On horses the flies 

 feed in greatest numbers on the lower parts of the legs, sides of the 

 neck and under the belly, although when an animal is in harness they 

 commonly feed on all parts of the body not readily reached l)y the tail. 



The bite of the fly is quite painful, the first insertion of the beak 

 being accompanied by a sharp, piercing pain. As the proboscis is 

 worked in further there is usually a series of more or less sharp pains 

 accompanied by itching. After the beak is inserted and feeding begins 

 there is usually no discomforture. Feeding is ordinarily completed 

 in from two to five minutes after the beak is inserted. After the fly 

 has once begun drawing blood it is usually not easily disturbed and 

 continues to feed until replete. When the fly is well filled excretion 

 of from one to several minute drops of a clear liquid usually takes 

 place. When the beak is withdrawn the fly goes through a series of 

 cleaning operations and flies away at the first sign of motion of the 

 host. Following the withdrawal of the beak a drop of blood usually 

 exudes. Little or no itching follows the bite although sometimes a 

 minute reddish spot is visible for a day or two. When fully engorged 

 the abdomen is tremendously distended and flight is comparatively 

 slow and heavy. 



For some time after feeding the flies are comparatively sluggish and 

 remain motionless on any nearby object. In open fields and along 

 roadways they were often seen during the recent outbreak in great 

 numbers beneath the surface of leaves of plants where they had gone 

 for protection from the sun during hot days, and hundreds of specimens 

 were often to be seen on the foliage of trees up to a considerable height. 

 Hundreds of them have often been observed resting on the shady sides 

 of barns and silos. During this resting period the blood digests rap- 

 idly and the voiding of th« clear liquid excrement occurs at intervals 

 of a few seconds. After a few hours this excrement becomes darker 

 and less liquid, leaving a black spot where it dries. During the out- 

 break des.cribed the weather boarding on houses and barns was in many 

 eases thickly spotted with this excrement. 



During moderately cool weather feeding usually takes place each 

 day. When the weather is warmer digestion proceeds faster and flies 

 imay engorge twice during one day. In some cases individuals which 

 are disturbed during their meal will persist until they have become 

 completely engorged, while others which are less persistent finally leave 

 the host when only partially fed. Flies have been observed to pass 



