HISTORY OF INSECTS, &c. 



BOOK III. 



INSECTS OF THE THIRD ORDER. 



CHAP. I. 



OF CATERPILLARS IN GENERAL. 



IF we take a cursory view of insects in general, 

 caterpillars alone, and the butterflies and moths 

 they give birth to, will make a third part of 

 the number. Wherever we move, wherever 

 \ve turn, these insects, in one shape or another, 

 present themselves to our view. Some, in 

 every state, offer the most entertaining spec- 

 tacle ; others are beautiful only in their wing- 

 ed form. Many persons, of which number I 

 am one, have an invincible aversion to cater- 

 pillars and worms of every species : there is 

 something disagreeable in their slow crawling 

 motion, for which the variety of their colouring 

 can never compensate. But others feel no re- 

 pugnance at observing, and even handling, 

 them with the most attentive application. 



There is nothing in the butterfly-state so 

 beautiful or splendid as these insects. They 

 serve, not less than the birds themselves, to 

 banish solitude from our walks, and to fill up 

 our idle intervals with the most pleasing spe- 

 culations. The butterfly makes one of the 

 principal ornaments of oriental poetry ; but in 

 those countries, the insect is larger and more 

 beautiful than with us. 



The beauties of the fly may, therefore, very 

 well excite our curiosity to examine the reptile. 

 But we are still more strongly attached to this 

 tribe from the usefulness of one of the number. 

 The silk-worm is, perhaps, the most serviceable 

 of all other animals; since, from its labours, and 

 the manufacture attending it, near a third part 

 of the world are clothed, adorned, and sup- 

 ported. 



Caterpillars may be easily distinguished 

 from worms or maggots, by the number of their 

 feet ; and by their producing butterflies or 



moths. 1 When the sun calls up vegetation, and 

 vivifies the various eggs of insects, the cater- 

 pillars are the first that are seen upon almost 

 every vegetable and tree, eating its leaves, and 

 preparing for a state of greater perfection. 

 They have feet both before and behind; which 

 not only enable them to move forward by a 

 sort of steps made by their fore and hinder 

 parts, but also to climb up vegetables, and to 

 stretch themselves out from the boughs and 



1 There is one tribe of caterpillar called Surveyors, or 

 Geometers, which walk by first fixing the fore- feet, and 

 then doubling the body into a vertical arch ; this action 

 brings up the hind part of the caterpillar, which is fur- 

 nished with prolegs, close to the head. The hind ex- 

 tremity, being then fixed by means of the prolegs situ- 

 ated at that part, the body is again extended into a 

 straight line ; and this process being repeated, the ca- 

 terpillar advances by a succession of paces, as if it were 

 measuring the distance, by converting its body into a 

 pair of compasses. At the same time that they employ 

 this process, they further provide for their security, by 

 spinning a thread, which they fasten to different points 

 of the ground, as they go along. 



Many other species of caterpillar practise the same 

 art of spinning fine silken threads, which especially as- 

 sist them in their progression over smooth surfaces, and 

 also in descending from a height through the air. The 

 caterpillar of the cabbage-butterfly, is thus enabled to 

 climb up and down a pane of glass, for which purpose it 

 fixes the threads that it spins in a zigzag line, forming so 

 many steps of a rope-ladder. The material of which 

 these threads are made, is a glutinous secretion, which, 

 on being deposited on glass, adheres firmly to it, and very 

 soon acquires consistence and hardness by the action of 

 the air. 



Other caterpillars, which feed on trees, and have often 

 occasion to descend from one branch to another, send out 

 a rope made with the same material, which they can pro- 

 long indefinitely; and thus either suspend themselves at 

 pleasure in the air, or let themselves down to the ground. 

 They continue, while walking, to spin a thread as they 

 advance, so that they can always easily retrace their 

 steps by gathering up the clue they have left, and re- 

 ascend to the height from which they had allowed them- 

 selves to drop. Dr Rogefs Bridgewater Treatise. 



