BEPOBT OF THE BUBEACT OF ANIMAL INDUSTRY. 459 



to pass the pupal stage, but transform where they happen to "be at 

 the time of reaching maturity, viz., in the swift current. While I 

 have observed the adult gnat emerge from the cocoon, after the latter 

 had been several hours before left above water by tne receding stream, 

 and a large number emerged in a cigar box in transit between Louis- 

 iana and Washington, D. C., I have never been able to secure adults 

 from pupae placed in jars of water, though kept in cool places, and 

 do not think they will live any length of time, even in this advanced 

 stage of development, in still or stagnant water. That larvae may, 

 during high water, be carried out of some streams into others where 

 none had previously existed, and these larvse pupate and develop to 

 adults, there is no question. Even ravines ordinarily dry in spring 

 are thus transformed into extensive breeding places, as is proven by 

 the great quantities of empty cocoons found there after the water 

 subsides. In no case, however, has this proven true where water 

 simply backed into such ravines, afterwards becoming stationary, 

 moving out again by the way it came, and not producing a running 

 stream. 



MODE OF ATTACK. 



Although flourishing in a subtropical country, apparently thor- 

 oughly adapted to their environment, these insects seem better cal- 

 culated by nature for a much cooler climate. Instead of reveling in 

 the heat and sunshine of midsummer they shun winter and summer 

 alike and appear in greatest numbers only during that portion of the 

 year when the temperature is the most moderate. 



In strict accordance with this characteristic adults are particularly 

 active during cool days and the cooler portions of warm days. As 

 I have stated, the adults are loth to forsake the vicinity of the cool 

 stream from which they emerge until night, which in the South is 

 invariably cool. Hence they are much more active and malignant 

 during cloudy days, late evening, and early morning. 



So also does the aquatic habit of the adolescent stages seem to in- 

 fluence the adults. They are always more numerous about shaded 

 lakes or ponds and in the woods, even low, damp, though not wet 

 ravines having considerable attraction for them. Often teams, when 

 at work in the fields, are attacked by gnats in overwhelming numbers 

 on approaching such places, while other localities are comparatively 

 exempt. I have, myself, when riding about on horseback, been sud- 

 denly beset by them in such myriads that it seemed as though they 

 would kill my horse beneath me before I could reach a place of safety. 

 During seasons of great abundance, however, they ao not confine 

 themselves to such favored localities, but seem to be everywhere 

 present and in about equal numbers. 



It is in times of great abundance that vast hordes of these insects 

 are carried about by the winds, and appear suddenly in localities 

 where they were not previously known. At such times cattle will 

 be grazing quietly in the fields, and teams at work without the least 

 indication of attack. But a gale of wind springs up, and in half an 

 hour everything is changed, and a motley collection of cattle, horses, 

 sheep, mules, and drivers come tearing in from the fields, each 

 trying to outstrip the others, all being goaded on by myriads of their 

 tormentors. Stock, and sometimes human beings, are killed in this 

 way before they can reach a place of safety. 



The gnats are extremely active, but so quiet in their movements 

 that they attract little attention. They fly low, seldom more than a 



