476 ' MOTIONS OF INSECTS. 



their cavity, and push themselves along, in the same manner as a chimney- 

 sweeper — by the pressure of his knees, elbows, shoukler-blacles, and other 

 prominent parts — pushes himself up a chimney.^ The hirvas of the ant- 

 lion (Myrmdion) , with the exception of one species, which moves in 

 the common way, always walks backwards, even when its legs are cut 

 off. 



The jumpers, amongst pedate larvae, as far as they are known, are not 

 very numerous, and will not detain you long. When the caterpillar of 

 Lithosia (Quadra, a moth not uncommon, would descend from one 

 branch or leap to another, it approaches to the edge of the leaf on which 

 it is stationed, bends its body together, and retiring a little backwards, 

 as if to take a good situation, leaps through the air, and, however high the 

 jump, alights on its legs like a cat. That of another moth {Herminia 

 rostralis) will also leap to a considerable height.^ 



Another species of motion, which is peculiar to larvae, — their mode I 

 mean of climbing, — as it merits particular attention, will occupy more 

 time. I have already related so many extraordinary facts in their history, 

 that I promise myself you will not disbelieve me if I assert that insects 

 either use ladders for this purpose, or a single rope. You may often 

 have seen the caterpillar of the common cabbage-butterfly climbing up 

 the walls of your house, and even over the glass of your windows. 

 When next you witness this last circumstance, if you observe closely the 

 square upon which the animal is traveling, you will find that, like a 

 snail, it leaves a visible track behind it. Examine this with your micro- 

 scope, and you will see that it consists of little silken threads, which it 

 has spun in a zigzag direction, forming a rope-ladder, by which it ascends 

 a surface it could not otherwise adhere to. The silk as it comes from the 

 spinners is a gummy fluid, which hardens in the air; so that it has no 

 difficulty in making it stick to the glass. Many caterpillars that feed 

 upon trees, particularly the geometers, have often occasion to descend 

 from branch to branch, and sometimes, especially previously to assuming 

 the pupa, to the ground. Had they to descend by the trunk, supposing 

 them able to traverse with ease its rugged bark, what a circuitous route 

 must they take before they could accomplish their purpose ! Providence, 

 ever watchful over the welfare of the most insignificant of its creatures, 

 has gifted them with the means of attaining these ends, without all this 

 labor and loss of time. From their own internal stores they can let 

 down a rope, and prolong it indefinitely, which will enable them to 

 travel where they please. Shake the branches of an oak or other tree 

 in summer, and its inhabitants of this description, whether they 

 were reposing, moving, or feeding, will immediately cast themselves 

 from the leaves on which they were stationed ; and however sudden 

 your attack, they are nevertheless still provided for it, and will all 

 descend by means of the silken cord just alluded to, and hang suspended 

 in the air. Their name of geometer was given to a large division of 

 the caterpillars which have this power of descending by silken threads, 

 because they seem to measure the surface they pass over, as they walk, 

 with a chain. If you place one upon your hand, you will find that they 

 draw a thread as they go ; when they move, their head is extended as 



» Anatom. Comp. i. 430. * Rosel, I. iv. 112. vi. 14. 



