1890.] 



THE YOUNG NATURALIST. 



29 



reproduction. I think no one will dispute the assertion that all 

 known insects are descended from flying ancestors. Do not con- 

 found this statement with that made previously, that the ancestor of 

 our insects was a vermiform, segmented, land animal, something like 

 Peripatus. What I wish to convey to you is that all insects of which 

 we have any fossil remains were winged ; and that existing wingless 

 forms, even such as lice, have come through, in the distant past, a 

 winged state. Now the question is how and why have some insects 

 ceased to use these once advantageous wings. When we find that 

 all our Macro-Lepidopterous apterous females (with two exceptions) 

 occur in cold and stormy weather we shall at any rate see, that light and 

 airy wings would be of little use, in fact of positive disadvantage ; of 

 course I am not overlooking the fact that the males of these species are 

 fully winged, but more of that later. It is curious too, that the males of 

 these apterous species are usually of light colour with large wings, and 

 are consequently conspicuous objects since they rest with their wings 

 more or less expanded, and the trees and hedges being out of leaf they are 

 very easily seen. Now this being so, we can well imagine, that those 

 individuals of more sluggish habits would be less likely to suffer from 

 the wintry storms, that any tendency to smaller size of wings would 

 give their possessor a better chance of surviving their then numerous 

 enemies, that any marked decrease in size which enabled the insect to 

 hide in crevices of tree trunks and would also give it a better chance 

 of reproducing its species ; these causes operating and accumulating 

 through many generations would produce the effects which we see. 

 A further factor tending to the preservation of and supplementing 

 these modifications is that arrangement of color which is commonly 

 spoken of as protective mimicry. We know that in hard cold weather 

 insectivorous birds are compelled to hunt very keenly for their food, 

 and therefore large or conspicuous insects are seen and captured. 

 The apterous females are small and inconspicuous when compared 

 with the males ; we can see then how much more likely they are to be 

 overlooked, in fact, it is well known amongst entomologists than unless 

 you breed these apterous females, or take them in cop, you have 

 great difficulty in obtaining them. 



It may be asked why is it that the males also have not lost their 

 wings ? to this it must be replied, the males are usually more active 

 than the females throughout the whole class Insecta, this is more es- 



