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escape. I Avould take as a simple illustration the case of certain species 

 of large grasshoppers (Oedipoda miniatum, Pallas, and caerulescens, L.), 

 familiar to all лvho have traversed the stony slopes of a Swiss mountain 

 These insects have bright red or blue hind wings, which are displayed 

 only in flight, and луЬеп at rest are folded up and completely concea- 

 led under the fore wings. The fore wings themselves are essentially 

 protective in their coloration, absolutely ressembling the grey stones 

 amongst which they rest. When the insect is disturbed, it takes a short 

 and rapid flight, remaining on the wing just long enough to attract the 

 eye to its conspicous colour, and alights suddenly and abruptly, usu- 

 ally at an angle from its direct line of flight, and is immediately con- 

 cealed by its protective ressemblance to the surroundings. The very 

 sudden loss of the conspicuous guiding colour of the hind wings so 

 completely deceives the eye that there is much more difficulty in mar- 

 king the spot on which the insect alights than there would be if such 

 colour had never been displayed. In California! noticed a very similar 

 instance in one of the Ardiadae (or Catocalidae), which had precisely 

 similar habits. It frequented the dry stones in the bed of a river left 

 by the shrinking of the water to its summer limits. It had orange hind 

 wings with black bars or mottlings, which were very conspicuous during 

 its short flights, but on alighting it became almost absolutely invisible, 

 the fore wings being coloured exactly as the stones among which it 

 dropped, and from which it was not easily disturbed. 



In our own country we have conspicuous instances in the genera 

 Catocala, Triphaena, Heliodes, and others. AVho has not noticed the de- 

 ceiptive effect of the bright yellow under wings displayed in the short 

 flights of Triphaena pronuba, and the extreme difficulty of following 

 its movements at the moment when these are no longer visible, as it 

 darts down among the grass-roots, where it is often extremely difficult 

 to detect or to dislodge? If this protective effect of the partial and inter- 

 mittent display of brilliant colouring is so obvious in relation to the 

 human eye, must it not be at least equally so in relation to the eyes 

 of its more natural enemies, such as birds, and have we not here indi- 

 cated a new and distinct line of investigation as regards the use and 

 advantage of brilliant colours in many cases which cannot be accounted 

 for by the theory that they are developed for the purpose of warning, 

 or through their aestetic relation to courtship? Mr. P о u 1 1 о n has at- 

 tempted to account for some of these appearances by the idea that 

 birds in pursuit of insects would strike with their beaks at the most 

 conspicuous part, and that the body or more vital part would be thus 

 protected at the expense of a few chips out of the hind wings; but in 

 some instances, especially in exotic Ardiadae, the body itself is the 

 more conspicuous and ornamented part of the insect. For such cases 

 this theory, however partially true it may be, would fail to account; 

 moreover, it can scarcely be denied that the insect, if less conspicuous 

 in its flight, would be less likely to attract the attention of the bird, 

 and therefore less liable to attack". 



PyccK. Эцтом. Обозр. 1905. Л: 5- 6. (Декабрь). 



15^ 



