THE GNAT TIPULA. 



555 



which she makes use of as a tongue, has tasted 

 any fruit, flesh, or juice, that she has found 

 out; if it be a fluid, she sucks it up, without 

 playing her darts into it ; but in case she 

 finds the least obstruction by any flesh what- 

 ever, she exerts her strength, and pierces 

 through it, if possibly she can. After this she 

 draws back her stings into their sheath, 

 which she applies to the wound in order to ex- 

 tract, as through a reed, the juices which she 

 finds inclosed. This is the implement with 

 which the gnat performs her work in the sum- 

 mer, for during the winter she has no manner 

 of occasion for it. Then she ceases to eat, 

 and spends all that tedious season either in 

 quarries or in caverns, which she abandons at 

 the return of summer, and flies about in search 

 after some commodious ford, or standing water, 

 where she may produce her progeny, which 

 would be soon washed away and lost, by the 

 too rapid motion of any running stream. The 

 little brood are sometimes so numerous, that 

 the very water is tinged according to the col- 

 our of the species, as green, if they be green, 

 and of a sanguine hue, if they be red. 



These are circumstances sufficiently extra- 

 ordinary in the life of this little animal ; but 

 it offers something still more curious in the 

 method of its propagation. However similar 

 insects of the gnat kind are in their appear- 

 ance, yet they differ widely from each other 

 in the manner in which they are brought forth, 

 for some are oviparous, and are produced from 

 eggs : some are viviparous, and come forth in 

 their most perfect form ; some are males, and 

 unite with the female ; some are females, re- 

 quiring the impregnation of the male ; some 

 are of neither sex, yet still produce young, 

 without any copulation whatsoever. This is 

 one of the strangest discoveries in all natural 

 history ! A gnat separated from the rest of 

 its kind, and inclosed in a glass vessel, with 

 air sufficient to keep it alive, shall produce 

 young, which also, when separated from each 

 other, shall be the parents of a numerous pro- 

 geny. Thus, down for five or six generations, 

 do these extraordinary animals propagate with- 

 out the use of copulation, without any congress 

 between the male and the female, but in the 

 manner of vegetables, the young bursting from 

 the body of their parents, without any previous 

 impregnation. At the sixth generation, how- 

 ever, their propagation stops ; the gnat no 

 longer produces its like, from itself alone, but 

 it requires the access of the male to give it 

 another succession of fecundity. 



The gnat of Europe gives but little uneasi- 

 ness ; it is sometimes heard to hum about our 

 beds at night, and keeps off the approaches of 

 sleep by the apprehension it causes ; but it is 

 very different in the ill-peopled regions of 

 America, where the waters stagnate, and the 



climate is warm, and where they are produced 

 in multitudes beyond expression. The whole 

 air is there filled with clouds of those famished 

 insects, and they are found of all sizes, from 

 six inches long to a minuteness that even re- 

 quires the microscope to have a distinct per- 

 ception of them. 1 The warmth of the mid-day 

 sun is too powerful for their constitutions ; but 

 when the evening approaches, neither art nor 



1 Under the common names of gnat and musnuito^ a 

 numerous family are confounded, as if there were only 

 one or two species ; whereas Mr Stephen has enumerated 

 twenty-two species of the genera Culex and Anopheles, 

 found in Britain alone ; and hence, it is probable, the 

 foreign musquitoes are also of several species, though to 

 common observers they do not appear to differ from the 

 common gnat. 



The Musquito-fly is very common in the woody and 

 marshy parts of all hot climates. It also abounds, dur- 

 ing their short summer, throughout Lapland, Norway, 

 and Finland, and other countries equally near the pole. 

 The female bites, and sucks the blood in such a severe 

 manner, as to swell and blister the skin very severely, 

 and sometimes leave obstinate sores. These insects are 

 found in such swarms, in the woods, that whoever enters 

 them is sure to have his face covered, and he is scarcely 

 able to see his way before him. A swelling and dis- 

 agreeable itch instantly follows the puncture, and these 

 are succeeded by small white ulcers ; so that the face of a 

 person coming from the country is scarcely to be recog- 

 nised, and it appears full of blotches. Even gloves are 

 not always found a protection against these troublesome 

 insects, as they often pass their stings through the seams. 

 It is the female only that bites ; the buzzing, however, of 

 both males and females is so very loud, as to be alone 

 sufficient to disturb the rest of persons at night. 



The Ox Gad-fly has brown unspotted wings ; and the 

 abdomen is marked with a black band in the middle, and 

 has dusky yellow hairs at the tip. The front is white, 

 and covered with down ; and the thorax is yellowish be- 

 fore, black in the middle, and cinereous behind. The 

 female differs from the male in having a black style at 

 the end of the abdomen. This insect deposits its eggs 

 in the back of the ox, and the larvae live beneath the 

 skin, between this and the cellular membrane. Its sac 

 or abscess is somewhat larger than the insect, and by 

 narrowing upwards, it opens externally to the air by a 

 small aperture. The Ox Gad-fly is the largest of the 

 European species, and is very beautiful: it is, however, 

 the terror of cattle, as it inflicts great pain when depo- 

 siting its eggs. 



The Horse Gad-fly is distinguished from the rest of 

 its tribe by having a black hand in the middle and two 

 dots at the tip of its whitish wings. The abdomen is 

 yellow brown, with black spots at the divisions of the 

 segments. The female is more brown than the male, 

 and has her abdomen elongated with a cleft terminal 

 style. The larvae are those odd-looking grubs which are 

 commonly found in the stomachs of horses, and some- 

 times, though much less frequently, in the intestines. 

 Here they hang in clusters of from half a dozen to more 

 than a hundred, adhering to the inner membrane of the 

 stomach, by means of two small hooks or tentaculre at 

 their heads, whose points turn outward. When they are 

 removed from the stomach, they will attach themselves 

 to any loose membrane, even to the skin of the hand. 

 To etiect this they draw back their hooks, which have a 

 joint near their base, almost entirely within their skin; 

 till the two points come close to each other ; then, keeping 

 them parallel, they pierce through the membrane, aiid 

 immediately afterwards expand in a lateral direction ; 

 and by these means they become perfectly fixed. 



