506 REPORT OF THE COMMISSIONER OF AGRICULTURE. 



former, there are numerous x^iaces %¥liere larvae can securely fasten 

 themselves, because large numbers of sticks partly embedded in mud 

 are not disturlied by the rising water. Against such immersed sticks, 

 as well as against fence-rails, &c., which cross such streams, numer- 

 ous dead leaves are lodged and *inchored by the mud. All such ob- 

 structions, forming small whirlpools just below them, are places in 

 which the larvae of the Turkey Gnats are found. Larger submerged 

 logs, wholly or partly submerged stum2:)S, brush, bushes, or any other 

 material of like nature in the larger creeks and bayous give the larvae 

 of the Buffalo Gnat suitable places to anchor to. 



Upon such material they cluster together, and, fastened by the pos- 

 terior protuberance to the leaf, they assume an erect position, or make 

 their way upward or downward with a looping gait. Frequently at- 

 tached by a minute thread, they sway with the ripj^les at or near the 

 surface of the water, often as many as half a dozen being attached by 

 a single thread. While these larvae make their way up and down 

 these submerged objects with perfect freedom they do not venture 

 above the water, and when about to pupate select a situation well 

 down toward the bottom of the stream. 



The larvae of the Turkey Gnat are more often found fastened to 

 submerged dead leaves in the smaller and more shallow creeks or 

 branches. These larvae are evidently somewhat social in their habits, 

 as they crowd together upon one leaf in numbers varying from ten to 

 thirty, and, judging from their uniform size, they must be the offspring 

 of the same iDarent. As the current aAvay from obstructions caused 

 by twigs and leaves, decreases in swiftness, so do the larvae decrease 

 in numbers, until only a few feet away but one or two can be found. 

 When first found, in early March, they are quite small, but they grow 

 rapidly during the latter part of March and early April. They are 

 quite stationary when not disturbed. Besides being fastened to the 

 leaf by the last posterior segment, they are also securely anchored by 

 a very fine silken thread. When disturbed they loosen their hold at 

 once and float downstream, suspended and retarded by this thread, 

 which very rapidly increases in length while the larvae are drifting with 

 the current. While thus drifting they jerk about in a lively manner, 

 searching for a new resting-place, and sink to the bottom quite grad- 

 ually. Oyring to their small size, and to the fact already stated, that 

 their color is in harmony with their surroundings or with the leaf 

 upon which they are fastened, these larvae are difficult to detect in a 

 depth of 3 to 4 inches. When removed and put in a glass vessel they 

 soon settle against the sides of their prison, and can then be studied 

 with a lens. 



The larva can move about very rapidly in the manner of a span- 

 worm, but with this difference, that it always remains anchored by 

 means of a thread, which lengthens as the animal proceeds. Being 

 very restless and actiA^e in such confinement, it will keep on looping 

 for hours, at a rate of twenty to twenty-five loops per minute. It can 

 move both forward and backward; the forward motion being pro- 

 duced by fastening the single thoracic leg to the side or bottom of the 

 vessel, loosening the anal proleg, bringing it close to the former, and 

 letting the latter go at almost the same moment; the backward motion 

 being simply a reversal. In the course of six to eight hours the larva 

 becomes weak and sickly; it will drop to the bottom of the vessel if 

 disturbed, but will no longer try to escape. All the larvae thus im- 

 prisoned, in repeated trials, died in the course of twenty-four hours. 

 A colony of nearly full-grown larvae, in a small creek, shared the 



