LOCALITIES OF INSECTS. 157 



(Hipparchia Semele), on the Knockagh, near Carrick- 

 fersrus, and on the strand at Portstewart ; the other, 

 the painted lady {Cynthia Cardui) , near the town of 

 Antrim, on one occasion only. 



In speaking of the latter, Mr. Knapp remarks, — 

 " This is a creature that visits us at very uncertain 

 periods, and is vivified by causes infinitely beyond the 

 comprehension of the Entomologist, seeming to re- 

 quire a succession and variety of seasons and their 

 changes, and then springing into life we know not 

 how." * 



From what has been stated, it is obvious that the 

 butterflies of different disti-icts differ much from each 

 other. The same holds good with respect to all the 

 other insect tribes, and gives an additional stimulus 

 to the exertions of the collector and the entomologist. 

 It is, however, a very curious subject for observation 

 and inquiry. The question continually recurs, — 

 Why are they so local } "^liy, when we can detect 

 no difference in the temperature or in the produc- 

 tions of two adjoining districts, are insects to be 

 found in the one, which are never met with in the 

 other ? To this we can give no satisfactory reply. 

 It is one of those things to which human knowledge 

 has not yet attained. It is, perhaps, a mystery 

 which we shall never be able to unfold. Who could 



* Journal of a Naturalist, p. 290. 



