COS 



SUPPLEMENT 



be so numerous in years favourable to their 

 propagation." Few insects, however, long sur- 

 vive their last transformation ; and notwith- 

 standing their amazing fecundity , mankind suf- 

 fer comparatively small annoyance from them, 

 in consequence of the voracity with which they 

 prey on each other, and the avidity with which 

 they are sought and devoured by birds and other 

 animals. The eggs of insects are for the most 

 part opaque objects, and admit only the ex- 

 amination of their outer surface ; in some few 

 instances, however, they can be viewed by 

 transmitted light when the interior structure 

 presents not unfrequently the most surprising 

 and interesting phenomena. 



From the egg the insect emerges into the 

 larva, or caterpillar state, which exhibits a won- 

 derful variely of structure and beauty of detail, 

 wholly dependent upon the microscope for their 

 satisfactory developement. This period of 

 insect existence, with all the interesting phe- 

 nomena therewith connected, will be rendered 

 perfectly familiar by the instances we have 

 selected for description and illustration. 



" The larva of the musca chamelion lives 

 in the water, breathes by the tail, and carries 

 its legs within a little snout near its mouth. 

 Itappears to consist of twelve annular divisions; 

 by these it is separated into a head, thorax, 

 and abdomen ; but as the stomach and intes- 

 tines lie equally in the thorax and abdomen, 

 it is not easy to distinguish their limits till 

 the insect approaches the pupa state. The 

 parts most worthy of notice are the tail and 

 snout. The tail is furnished with an elegant 

 crown or circle of hair, disposed quite round 

 in an annular form ; by means of this the 

 tail is supported on the surface of the water, 

 while the worm or larva is moving therein, 

 the body in the meanwhile hanging towards 

 the bottom ; it will sometimes remain in this 

 situation for a considerable time, without the 

 least sensible motion. When it is disposed 

 to sink to the bottom by means of its tail, it 

 generally bends the hairs of that part towards 

 each other in the middle, but much closer 

 towards the extremity ; by these means a 

 hollow space is formed, and the bladder of air 

 pent up in it, looks like a pearl. It is by the 

 assistance of this bubble, or little balloon, that 

 the insect raises itself again to the surface of 

 the water. If this bubble escape, it can re- 

 place it from the pulmonary tubes ; sometimes 

 large quantities of air may be seen to arise in 

 babbles from the tail of the worm to the sur- 

 face of the water, and there mix with the in- 

 cumbent atmosphere. This operation may be 

 easily seen by placing the worm in a glass 

 lull of water, where it will afford a very en- 

 tertaining spectacle. The snout is divided 

 into three parts, of which that in the middle 

 is immovable ; the two other parts grow from 



the sides of the former ; these are movable, 

 vibrating in a very singular manner, like the 

 tongues of lizards and serpents. The greatest, 

 strength of the creature is fixed in these 

 lateral parts of the snout ; it is on these that 

 it walks when it is out of the water, appear- 

 ing, as it were to walk on its mouth, using it 

 to assist motion, as a parrot does its beak, to 

 climb, with greater advantage." 



" We shall now consider the external 

 figures of this worm, as it appears with the 

 microscope. It is small towards the head, 

 larger about those parts which may be con- 

 sidered as the thorax ; it then again diminishes, 

 converging at the abdomen, and terminates 

 in a sharp tail, surrounded with hairs in the 

 form of the rays of a star." 



" This worm, the head and tail included, 

 has twelve annular divisions. Its skin resem- 

 bles the covering of those animals that are 

 provided with a crustaceous habit, more than 

 it does that of naked worms or caterpillars ; it 

 is moderately hard, and like the rough skin 

 called shagreen, being thick set with a num- 

 ber of grains, evenly distributed. The sub- 

 stance of the skin is firm and hard, and yet 

 very flexible. On each side of the body are 

 nine spiracula or holes, for the purpose of re- 

 spiration ; there are no such holes visible on 

 the tail ring, nor on the third ring counting 

 from the head ; for at the extremity of the tail 

 there is an opening for the admission and ex- 

 pulsion of air ; in the third ring the spiracula 

 are very small, and appear only under the 

 skin, near the place where the embryo wings 

 of the future fly are concealed. The skin 

 has three different shades of colour ; it is 

 adorned with oblong black furrows, with spots 

 of a light colour, and orbicular rings, from 

 which there generally springs a hair, as in the 

 figure before us. Only the hair that grows on 

 the insect's side is represented. The differ- 

 ence in colour in this worm arises from the 

 quantity of grains in the same space ; for in 

 proportion as there is a greater or less quantity 

 of these, the furrows or rings are of a deeper 

 or paler colour. The head is divided into 

 three parts, and covered with askin, the grains 

 on which are hardly discernible. The eyes 

 are rather protuberant, and lie forwards near 

 the snout. It has also two small horns on the 

 fore part of the head, and a little above these 

 the eyes are situated. The snout is crooked, 

 and ends in a sharp point. 



" The tail is constructed and planned with 

 great skill and wisdom. The extreme verge 

 or border, is surrounded by thirty hairs, and 

 the sides adorned with others that are smaller; 

 here and there the large hairs branch out into 

 smaller ones, which maybe reckoned as single 

 hairs. These hairs are all rooted in the outer 

 skin,which in this place is covered with rough 



