288 MOTIONS OF INSECTS. 



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 3 . 



Another species o 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 hi- 

 story, that I promise myself you will not disbelieve me 

 if I assert that insects either use ladders for this pur- 

 pose, 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 cir- 

 cumstance, if you observe closely the square upon which 

 the animal is tavelling, you will find that, like a snail, it 

 leaves a visible track behind it. Examine this with 

 your microscope, and you will see that it consists of 

 little silken threads, which it has spun in a zigzag direc- 

 tion, forming a rope-ladder, by which it ascends a sur- 

 face it could not otherwise adhere to. The silk as it 

 comes from the spinners is a gummy fluid, which hard- 

 ens 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 ac- 

 complish their purpose ! Providence, ever watchful 

 a Rosel, I.iv. 112. vi. 14. 



