FLIGHT OF INSECTS. 05^ 



which has hut a small wine;, contains, according to Lewen- 

 hoeck, more than two hundred thousand of these scales in 

 each wing. 



These scales douhtless contrihute to the protection of the 

 wing; but they at the same time add considerably to their 

 weight, and impede the velocity of their action. This in- 

 convenience appears to have been in a great measure com- 

 pensated by the greater size of the wings, and by the extent 

 of the surface with which they strike the air. Still, how- 

 ever, it is sufficiently obvious that insects of this order fly 

 with less rapidity and steadiness than most others. But this 

 unsteadiness, again, is turned to good account; for the but- 

 terfly, by its irregular and apparently capricious movements, 

 alternately dipping and rising in the air, so as to describe a 

 series of zigzag lines, more easily eludes capture when pur- 

 sued, not only by naturalists, but also by birds that are ea- 

 gerly seeking to secure them. It is astonishing to what a 

 distance the silk worm motiis will fly: some have been 

 known to travel more than a hundred miles in a short time. 

 The PapUio Iris often rises to so great a heiglit in the air 

 as to be quite invisible. 



A mechanical contrivance is adopted in many of the Le- 

 pidoptera for keeping their wings steady during flight, con- 

 sisting of a hook covered with hair and scales, attached to 

 the under side of the upper wings near their ijase, and con- 

 nected also by means of bristles to the base of the lower 

 wing: by this attachment. all the wings are locked together 

 and brought into action at the same time. Insects of the 

 Sphinx tribe are also provided with a kind of rudder formed 

 by the expansion of the tail, enabling them to steer their 

 course with more certainty. The Lcpidojitera in general 

 fly with the body nearly upright, contrary to the habits of 

 most other winged insects, whose bodies, while flying, are 

 nearly in a horizontal position. 



The feats of agility and strength exhibited by insects have 

 often been the theme of admiration with writers on natural 

 history; and have been considered asaflbrding incontrovert- 

 ible proofs of the enormous power with which their muscles 



