104! ME. R. M^LACnLAN ON THE TNSECTA COLLECTED 



for these insects to appear in the perfect state, and that about six 

 weeks is the limit of time allowed to plant-feeding larvae, during 

 all the rest of the year the land being under snow and ice. This 

 latter fact is suggestive, as showing the conditions under which 

 the species maintain an existence. AVe have, however, much yet 

 to learn respecting their life-history. The intense cold is not of 

 great importance. We know already that larvae may be frozen 

 till they are as brittle as rotten twigs, and still suffer in no way. 

 The principal point may be put as follows : — Is there sufl&cient 

 time in each year for a larva to hatch from the egg, feed up, and 

 change to chrysalis ? The continuous day, no doubt, acts benefi- 

 cially in this respect on the larvae of butterflies, such as Colias 

 and Argynnis, which probably feed only in the day-time ; but it 

 must act in the contrary manner on those of Noctuce, &c., which 

 practically feed only at night. Upon reviewing all these conditions, 

 I am disposed to think that more than one year is necessary in 

 most of the species for the undergoing of all their transformations. 

 This indeed is already suspected in certain species that inhabit 

 the boreal and alpine portions of Europe. 



The Diptera furnish but few points of special interest. "When 

 oifal was thrown away, or the carcass of a Musk-ox lay on the 

 ground, "blow-flies" appeared ready to perform the scarcely ne- 

 cessary part of scavengers. The genus Trichocera, known with us 

 as the "winter-gnat," appeared after midsummer, the only time 

 it can appear if the genus be allowed to exist at all. Most 

 travellers in high latitudes have complained of the attacks of 

 the myriads of Culicidae. I am informed that this expedition 

 proved no exception when off" the lower portions of the coast of 

 Grreenland ; but the members of it did not suff'er in the extreme 

 north, although Culicidae were not uncommon. 



The few remaining orders of insects ofl'er occasion for no special 

 remarks. 



Regarding the collections as a whole, I should say there is 

 evident afSnity (in some cases absolute identity) with the fauna 

 of Lapland ; but, notwithstanding all that has been urged to the 

 contrary, I incline to the belief in a former extensive circumpolar 

 fauna, of which there now exist but remnants. (I would mention 

 incidentally also that I do not think the two great divisions known 

 as the Palaearctic and Nearctic can be maintained for insects, ex- 

 cepting as terms of convenience.) "We know that in Miocene 

 times there existed in the latitudes with which we are now deal- 



