THE EFFECT OF METEOROLOGICAL CONDITIONS. 



210 



July, 1858—88. 1888. 



Mean temperature G4'5° 59'2° 



at t) a.m. 



Absolute maximum 80-0° 75-9° 



Average maximum 74-7° 07-3° 



Average minimum 54-0° 52-3° 



Absolute minimum 4-5'2° 42-8'^ 



Comparison with former Years. 



In ]879, also 59-:>°; no other 

 year below 60°. 



In 186U, also 750°; no other 

 year so low. 



1879, 07-7°; 1875, 09-8°; 1800, 

 G9-9°. 



1863, — lowest on record, — 50"2° ; 

 and there are nine other in- 

 stances lower than reached this 

 year. 



1863, — lowest on record, — 40-3° ; 

 five other lower registrations in 

 previous years. 



" Hence," Mr. Symons remarks, " altliough the minima have 

 not been excessively low, the maxima have been low beyond all 

 precedent for 30 years, and it is to that, coupled with continuous 

 and heavy, though not unprecedented, rain, that all the discomfort 

 and loss is due." 



The practical economic effect of these conditions upon insect- 

 life is a matter of equal interest to the entomologist and the farmer, 

 and the subject is one that is well worthy of special study. 



It has been mooted by more than one writer that melanism is 

 produced simply by atmospheric conditions, being due either 

 directly to local humidity (see Mr. T. D. A. Cockerell's paper in 

 Entom., vol. xx., pp. 58 — 9), or indirectly, as a consequence of 

 moisture, to the darkening of the wood-surfaces to which the 

 insects cling (' On Melanism in Lepidoptera,' by Dr. T. A. Chap- 

 man, E. M. M., vol. XXV., p. 40). Neither theor}' can, I think, 

 be said to furnish a satisfactory explanation, and the evidence yet 

 produced is of the slightest nature ; but on the supposition that 

 either be true, we should certainly this year have, as a result, a 

 very large proportion of melanic forms throughout the country, 

 and the rare opportunity thus afforded of practically testing the 

 validity or otherwise of these suggestions by observation should 

 not be lost. 



It must, however, be well borne in mind that lateness of 

 appearance of any species is not, of course, necessarily connected 

 with this particular season. Numerous instances of retarded 

 emergence are annually recorded in these pages, and in illustration 

 I may cite that I have two pupse of Euchloe cardamines wliich 

 have not yet developed, though apparently living, while several 



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