Climatic Causes affecting the distribu 
tion of Lepidoptera in Great Britain. 
Bevin 0. WALK ER, FF. L.8: 
Read before Lancashire and Cheshire Entomological Society, 
July 30th, 1883. 
{EW people can have undertaken the study of any class of 
Animals or Plants without being struck by the unaccount- 
able way in which many species are confined to limited areas. 
And this is especially remarkable in the case of winged insects, 
such as the Lepidoptera, provided with powerful means of 
locomotion, and, in addition, liable to be carried considerable 
distances against their will by gales of wind. Yet it is notorious 
that many species are confined to extremely small areas, and 
even to one particular field in a large district. 
Let me say at the outset that I am fully aware of the 
difficulties of the subject. The number of persons able and 
willing to make and record observations on the occurrence 
even of so popular a class of Insects as the Lepidoptera is very 
limited, especially in those districts where Butterflies and Moths 
are not very abundant, or where, as in North Wales, there are 
no large towns to act as centres of intellectual energy, and the 
number of species recorded will certainly be affected by the 
number of recorders. Again a very slight preponderance of 
larva breeders or ‘‘sugarers”’ in any district will lead to a 
greater number of Bombycina or Noctuina respectively being 
recorded there as compared with other orders. Yet in spite of 
these and other difficulties, I believe that a tolerably fair com- 
parison may be made between districts which have been worked 
by good Entomologists. The district adopted by the Chester 
Society of Natural Science, consisting of Cheshire W. of a line 
drawn 8S. from Warrington, with the Counties of Flint and 
Denbigh, has been well worked in the Hundred of Wirral by 
the late Mz. BrocxHoies (who published a list of the Lepidop- 
tera many years ago), Mr. Cooxg, and no doubt others; also on 
the E. side by the late Mr. Noan Gnreentne, who furnished me 
with a list of captures on our side of Warrington. The Welsh 
portion, and that near Chester to the S, and E., has been but 
