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LETTER XXV. 

 ON LUMINOUS INSECTS. 



We boast of our candles, our wax-lights, and our Argand 

 lamps, and pity our fellow-men who, ignorant of our methods 

 of producing artificial light, are condemned to pass their nights 

 in darkness. We regard these inventions as the results of a 

 great exertion of human intellect, and never conceive it pos- 

 sible that other animals are able to avail themselves of modes 

 of illumination equally efficient, and are furnished with the 

 means of guiding their nocturnal evolutions by actual lights, 

 similar in their effect to those which we make use of. Yet 

 many insects are thus provided. Some are forced to content 

 themselves with a single candle, not more vivid than the rush- 

 light which glimmers in the peasant's cottage ; others exhibit 

 two or three, which cast a stronger radiance ; and a few can 

 display a lamp little inferior in brilliancy to some of ours. 

 Not that these insects are actually possessed of candles and 

 lamps. You are aware that I am speaking figuratively. But 

 Providence has supplied them with an effectual substitute — 

 a luminous preparation or secretion, which has all the advan- 

 tages of our lamps and candles without their inconveniences ; 

 which gives light sufficient to direct their motions, while it 

 is incapable of burning; and whose lustre is maintained 

 without needing fresh supplies of oil or the application of the 

 snuffers. 



Of the insects thus singularly provided, the common glow- 

 worm (Lampyris noctiluca) is the most familiar instance. 

 Who that has ever enjoyed the luxury of a summer evening's 

 walk in the country, in the southern parts of our island, but 

 has viewed with admiration these " stars of the earth and dia- 

 monds of the night?" And if, living like me in a district 

 where it is rarely met with, the first time you saw this insect 

 chanced to be, as it was in my case, one of those delightful 



