THE ENTOMOLOGIST. 



Vol. XV.] JANUARY, 1882. [No. 224. 



NOTES ON THE LEPIDOPTERA. OF THE ORKNEY ISLANDS. 

 By J. Jenner Weir, F.L.S., F.Z.S. 



The Orkney Islands lie between 58° 41' and 59° 23' N. lat., 

 and between about 2° and 3° W. long., thus being from 7° to 8° 

 north of London ; still the climate is mild. The average tem- 

 perature of February, the coldest month, is 38°, and of July, the 

 hottest month, 55° 14'. The rain-fall during the year averages 

 about 36f inches. These islands are separated from the north- 

 east of Scotland by the Pentland Firth, which, at the narrowest 

 part, is not more than 52- miles in width. The whole group, with 

 the exception of a small granitic district, near Stromness, consists 

 of rocks belonging to the old red sandstone formation ; thus their 

 geological structure differs essentially from that of either the 

 Shetlands or Outer Hebrides. 



Through the kindness of Mr. Meek I have been enabled to 

 examine a collection of Lepidoptera made in the Islands during 

 four months of the past season, which are in the possession of 

 Mr. Clarence E. Fr}^, through whose instrumentality they were 

 collected. As might be expected, from the near proximity of the 

 Islands to the North of Scotland, the insects do not in most cases 

 differ materially from those found on the mainland ; yet the col- 

 lection is most interesting, presenting in many of the species 

 differences in colour from that which obtains either in the Shet- 

 lands or Outer Hebrides. 



The following is a list of the Lepidoptera taken in the Island 

 of Hoy, about eight miles distant from the coast of Caithness, 

 and in which island alone were any insects collected : — 



'^'Pieris brassicce '^'Lyccena Icarus 



■•-Chortohius Davus Acherontia Atropos 



B 



