The Colouration of Insects. 69 



words can describe, especially when the apparent exceptions are 

 considered ; for many moths are as brightly coloured as butterflies. 

 These will be found to belong either to day-flying species, like the 

 various Burnets (Zygcena), Tiger Moths (Arctia), or evening flyers 

 like the Hawk Moths (Sphyngidce.) The true night-flying, darkness- 

 loving moths cannot in any way compare with the insects that 

 delight in sunshine. We see the same thing in birds, for very few 

 nocturnal species, so far as we are aware, are brilliantly decorated. 



Another salient feature is the difference that generally exists 

 between the upper and lower surfaces of the wings. As a rule, the 

 upper surface is the seat of the brightest colour. Most butterflies, 

 perhaps all, close their wings when at rest, and the upper wing is 

 generally dropped behind the under wing, so that only the tip is 

 visible. The under surface is very frequently so mottled arid 

 coloured as to resemble the insect's natural surroundings, and so 

 afford protection. It does not follow that this protective colouring 

 need be dull, and only when we know the habit of the insect can we 

 pronounce upon the value of such colouring. The pretty Orange- 

 tip has its under wings veined with green, and is most conspicuous 

 in a cabinet, but when at rest upon some umbelliferous plant, with 

 its orange tip hidden, these markings so resemble the environment 

 as to render the insect very inconspicuous. The brilliant Argynnis 

 Lathonia, with its underside adorned with plates of metallic silver, is 

 in the cabinet a most vivid and strongly-marked species; but we 

 have watched this insect alight among brown leaves, or on brown 

 stones, outside Florence, where it is very common, and find that 

 these very marks are a sure protection, for the insect at rest is 

 most difficult to see, even when it is marked down to its resting- 

 place. 



But some butterflies have parts of the under surface as gaily 

 decorated as the upper ; and this not for protection. This may be 

 seen to some extent in our own species, for instance in the orange- 

 tip of the Orange-tip, and the red bar in the upper wing of the Red 

 Admiral (V. atalanta}. If we watch these insects, the conviction that 

 these are true ornaments is soon forced upon us. TJie insect alights, 

 perhaps alarmed, closes its wings, and becomes practically invisible. 

 With returning confidence it will gradually open its wings and 

 slowly vibrate them, then close them again, and lift the upper wing 

 to disclose the colour. This it will do many times running, and the 

 effect of the sudden appearance and disappearance of the bright 



