REPORT OP THE ENTOMOLOGIST. 495 



distances beyond their usual haunts. At first the members compos- 

 ing a swarm are very active and blood-thirsty; but they soon die, and 

 the swarm decreases gradually and soon disappears entirely. New 

 sv;-arms appear continually and replace the former ones. The dura- 

 tion of an invasion throughout the regions infested varies from a few 

 days to five or six weeks. If cold weather follow their appearance, 

 the gnats become semi-dormant ; they are not killed by it nor by rain, 

 but revive and become aggressive again with the first warm rays of 

 the sun. Hot weather, however, soon kills them and puts an end to 

 any further injury. The duration of life of a single individual is 

 short; at least' specimens confined even in large and well-lit boxes 

 soon die. Buffalo Gnats that have once imbibed blood of any animal 

 also soon die, as seen by the large numbers found dried up in stables 

 in Avhich they have been carried attached to mules or horses. In the 

 , fields gnats filled to repletion with blood drop to the ground and 

 crawl away, soon to die. They suffer, therefore, from their blood- 

 thirsty habits, and this seems to be quite a general rule Avith all those 

 blood-sucking species which are known to annoy man and other warm- 

 blooded animals; for the love of blood generally proves ruinous to 

 those individuals which are anxious to indulge in it, as we have shown 

 to be the case with the Harvest Mite or Jigger.* 



CHARACTER OP A SWARM. 



The number of individuals comprising a swarm cannot be com- 

 puted, as swarms vary greatly in size. Their presence is at once in- 

 dicated by the actions of the various animals in the field. Horses 

 and mules snort, switch their tails, stamp the ground, and show great 

 restlessness and symptoms of fear. If not harnessed to plow and 

 wagon they will try to escape by running away. Cattle rush wildly 

 about in search of relief. Formerly, when deer were still numerous, 

 they would be so tormented by these insects as to leave their hiding- 

 places and run away, seeking protection even in the presence of their 

 greatest enemy, man. Approaching animals in the field,we notice at 

 once small black bodies, exceedingly swift in their flight, darting 

 about their victims in search of a suitable spot to draw blood. But 

 even during a very general invasion by these gnats these insects are 

 not uniformly distributed throughout the region infested, but they 

 select certain places. Only low and moist ground is frequented by 

 them; exposed or sunny spots are never visited. There may be no 

 indications of gnats in a whole neighborhood, and the unprei)ared 

 farmer, dreaming of no danger to his mules or horses in passing 

 dense thickets of bushes, &c., near the roadside, is suddenly attacked 

 by a swarm of these'pests, and is frequently unable to reach a place 

 of safety in time to save his cattle. As suddenly as such swarms ap- 

 pear, just as suddenly do they disappear. During a gnat season cau- 

 tious farmers never travel with their horses or mules without pro- 

 viding themselves with some kind of protective grease. 



When Buffalo Gnats are very nuinerous the whole air in the vicinity 

 of our domestic animals is filled with them at times, and looking to- 

 wards the suffering brute, one sees it surrounded by a kind of haze 

 formed by these flying insects. Sweeping rapidly with the hand 

 through the air one can collect hundreds of gnats by a single stroke. 

 They crawl into everything, and the plowman has constantly to brush 



*See Avier. Naturalist, vol. vii, 1873, p. 19. 



