INFLUENCE OF METEOROLOGICAL CONDITIONS ON LEPIDOPTERA. 27 



I am ignorant, having passed them on the Continent. But since 

 that year it cannot be said that a single season has been prolific. 

 Now the meteorologist's record that every summer since 1879 

 has been notably deficient in heat, so that we have had five cool 

 summers in succession ; while those of the years 1874 — 78, 

 inclusive, were above the average of warmth, — that of 1874 being 

 " warm;" 1875, of normal temperature (though wet) ; 1876, very 

 warm, inasmuch as there were only fourteen " cOol" days (con- 

 trasting with fifty-five in that of 1879) ; while the summer of 1878 

 was, although somewhat rainy, above the average temperature. 

 In the former period, that is before 1878, the rainfall averaged 

 5 per cent, in excess; in the latter no less than 18 per cent, 

 above the normal amount. 



Now as to the effect the amount of rainfall has upon the larvse 

 of lepidopterous insects, although I do not dispute it to be 

 perhaps considerable (especially, I am inclined to think, upon 

 day-feeders), yet I hold very strongly that sun heat is necessary, 

 next to food, in promoting health, growth, and, in fact, general 

 vital energy. 



While the largest number of lepidopterous insects, either in 

 larval or perfect state, do not object to damp (I refer to the 

 greater portion of nocturnal Heterocera), yet there can be no 

 question that all the Khopalocera, and nearly all the Heterocera, 

 are powerfully influenced by sunshine or warmth. A damp, nay 

 a wet, night, so long as it is warm, is excellent for entomological 

 research, not only for imagines, but for larvae. And when one 

 considers the numerous species that thrive in fenny and marshy 

 places, and the abundant lepidopterous fauna occurring in those 

 portions of the British Islands most noted for excessive rainfall, 

 namely, the Lake Districts, South Devon and Cornwall, the 

 South of Ireland and Killarney, the conclusion seems forced upon 

 one that rain and damp of themselves are not prejudicial to by 

 far the greatest section of the order of Lepidoptera. The damp 

 heat of the Tropics seems to be entirely congenial, whilst the 

 damp, but cold, climates of the world, on the other hand, seem 

 almost devoid of this description of insect-life. 



It is, of course, needless to offer any proof of the magical 

 power of sun heat on these beautiful creatures ; but a remarkable 

 illustration of it once occurred to me, which I am tempted to 

 adduce. Some few years since I had ascended one of the Swiss 



