( cxxxiv ) 



Olf a dragon-fly — treating itself as entitled to a certain beat 

 and driving off all intruders, but what appears to be the sheer 

 love of a tussle. How often a collector, after carefully stalk- 

 ing down a butterfly, finds all his plans defeated because some 

 other butterfly passes near the object of pursuit, which cannot 

 resist the temptation of dashing at the passing stranger — it 

 may be one of a quite different species — and then ensues a 

 mutual buffeting, the two insects rising out of sight. Sexual 

 attraction does not come in here; nor can the end be physical 

 training, such as results from the " play " of higher animals, 

 for a new-born butterfly inherits instincts which enable it to 

 fly perfectly as soon as its wings are dry. There are doubtless 

 many moths, especially females, to which these remarks about 

 activity do not apply, but they are applicable to a very large 

 nvimber of Lepidoptera, perhaps to most. 



General activities influenced hy conditions. 

 A consideration of the general activities of insects may 

 possibly bring us nearer to answering the question why 

 Lepidoptera are more abundant in some countries, especially the 

 warmer ones, than in England. All will agree that a full 

 measure of health and vigour is a necessary condition for 

 enabling a species in the competition that exists to hold its 

 own with complete success, the measure of this sviccess greatly 

 depending on the extent to which those conditions are adapted 

 to promote its health and vigour. 



Influences of tem/perature on activities. 

 We must all have observed the immense difference which 

 temperature makes in the activity of most of our Lepidoptera, 

 how cold paralyses their energies so that they can hardly be 

 provoked into movement ; in hot weather, on the contrary, the 

 lightest tap on a tree, or the gentlest touch on a hedge, will 

 cause them to fly out in numbers. Many butterflies ai^e 

 absolutely inactive whenever the sun is behind a cloud, and 

 I suggest that the necessity to these of sunshine for flight is 

 caused by their readiness to respond rather to a high temper- 

 ature than to intensity of light.* We warm-blooded ci'eatures 



* Though I think it deserves observation whether brightness alone as 

 compared with gloominess may not influence the movement of some 



