1S85.] 271 



INSECTS IN AECTIC REOIONS. 



[Extracted feom " Das Insektenleben is arktischen Landern, von 

 Christopher Aurivillius," 



POEMING PART OP NoRDENSKIOLD's " StUDIEN UND FoRSCHUNGEN YERANLASST DUECH 

 MEINE ReISEN IM HOHEN NoRDEN : " LEIPZIG, 1885.] 



A special interest attaches to the question of the mode of life in 

 insects in relation to their surroundings in high Northern latitudes. 

 Knowing, as we do, that the time available for the development of an 

 insect in the extreme North is limited to from 4 to 6 weeks in the 

 year, one has felt surprised how it could be possible for certain species 

 to run through all their transformations in so short a time. 



H. McLachlan, in his paper on the insects of Grrinnell Land 

 (Journ. Linn. Soc, Zoology, vol. xiv), refers to the difficulties which 

 the shortness of the summer interposes to the development of insects, 

 and intimates his suspicion that a development which would with us 

 take place in a single summer would there require several summers. 



The correctness of this suspicion has been completely established 

 by the interesting observations on species of Lepidoptera in South 

 Waranger, in latitude 69° 40', made by Gr. Sandberg. He was success- 

 ful in watching the development of some extreme Northern species 

 from the egg. 



Let us take as an example (Eneis Bore, Schn., a true hyperborean 

 butterfly, which has never been found outside the Arctic circle, and 

 even there only occurs in places which bear a truly Arctic stamp. 



The imago flies from the middle of June onwards, and lays its 

 eggs on various species of grass. The eggs are hatched the same 

 summer ; the larva hibernates below the surface of the earth, feeds 

 and grows all through the following summer, but does not succeed in 

 attaining its full size : it then hibernates a second time, and does not 

 assume the pupa state till the spring of the following year. 



The pupa, which in the allied forms in more southern localities 

 is freely suspended in the air to a grass-stem or some similar object, 

 here reposes in the earth, which in so inclement a climate must 

 evidently be a great advantage. 



The butterfly escapes from the pupa-skin after an interval of from 

 5 — Q weeks, a period of unusual length for a diurnal Lepidopteron. 

 In more southern lands the pupal repose of butterflies in summer 

 rarely exceeds a fortnight. Hence, the entire metamorphosis is more 

 tedious than in more temperate regions. 



By these and other observations, Sandberg shows that one Arctic 



