130 



On the Metamorphoses, $c. 



[July 



whirlpool again, and was as often seized, but with no better success. 

 They, however, eat the shells they had recently quitted. Some that 

 were kept in clean water, without food, died oh the third; day. In this 

 stage of their existence, the insects were lively and grew apace. 



At the termination of 21 days, during which the water was thrice 

 changed, they had attained three or four twentieths of an inch in 

 length. On attaining this size, or age, they underwent a second meta- 

 morphosis. The shape they assumed is represented in figure 2, mag- 

 nified, like the former, 2,500 times. Most likely they cast their former 

 envelope, for the hairs, so conspicuous on the former insect, were not to 

 be seen on the present. The shape, it will be lemarked, has materially 

 altered, but the most remarkable change is that which occurs with re- 

 spect to the seat of the lungs, or gills. These organs are now situate 

 in the thorax, their former seat (the elongation b. fig. 1) has disap- 

 peared, and the channel of communication, now, between them and the 

 air, are two small tubes (b. fig. 2) on the top of the chest. In this stage 

 of their existence, the insects are much less active than during the for- 

 mer one. A still greater contrast, however, is that, now, they do not 

 require food, and have no mouth; in this respect resembling the 

 chrysalis stage of the butterfly tribe. But the demand for air appears 

 increased ; they rarely leave the surface of the water, and, when they 

 do descend, they take down a supply of air, small globules of which are 

 distinctly to be observed, at the end of the tube (b. fig. 2). Their 

 descent is accomplished by striking the water with their body, but, 

 being specifically lighter than that fluid, they rise without any effort to 

 the surface, though, in case of despatch, can impel themselves upwards 

 by the same means as they descended. However, as has been remark- 

 ed,- they seldom leave- the surface, and, having done so, speedily re- 

 turn to it. 



The insects remain about 48 hours in this stage ; towards the ter- 

 mination of which the legs aud proboscis of the winged musquito can 

 be distinctly seen through the thin membrane that surrounds it. This, 

 in due course, bursts, when the winged musquito draws itself out, 

 stands on the surface of the water a few minutes, to dry and expand 

 its wings, on which it presently proceeds to a dry situation. I observ- 

 ed several undergoing this change. 



If the musquito, when in either of the first two stages, be taken out 

 of the water, it speedily dies, and it is as speedily deprived of life, if 

 immersed in that fluid immediately after becoming the winged insect. 



We learn from the above, that the musquito is a most prolific insect 

 and that, as stagnant water such as that of tanks, &c. is necessary 

 to its propagation, all such ought to be kept as distant as possible 

 from our dwellings; thereby we are more likely to enjoy an immunity 

 from their annoyance, than by practising the mode so facetiously 

 described, or rather suggested, by Captain Basil Hall in his voyages. 



