THE FIREFLY ATTRACTED TO LIGHT. 163 



•' Of the earlier stages of any of these light-bearing insects I 

 have been able to procure little information. About the middle 

 of May a larva of an Elateridous Beetle was brought to me 

 which was luminous ; in the dark the whole insect was pellucid, 

 but the divisions of the segments showed distinct light, blue and 

 pale, not very vivid. It was impatient of being handled, and 

 bit fiercely at the hand, but ineffectually. I suspect that it was 

 the larva of the Glow-fly. The specimen is now in the British 

 Museum. And at Content, in the latter part of July, I found 

 in fresh-turned earth a larva of a Lampyris, small and lengthened : 

 the abdomen, like that of the European glow-worm, was fur- 

 nished with a retractile brush of divergent filaments, ordinarily 

 concealed; but having no lens with me, I could not examine it 

 particularly." 



I may here mention that the light of the Cucujo has been tested 

 by the spectroscope, but with very little result, the spectrum 

 being merely a " continuous " one, i.e. without any bars across it, 

 either dark or luminous. I have tried the common glow-worm 

 by the same test, and found the same result. It is as well 

 with the latter insect to have several specimens together, as the 

 light is not nearly so powerful as that of the Cucujo. 



It is said that the Cucujo will fly to a lamp or torch, but this 

 statement has been denied by some travellers. That they have 

 not succeeded in attracting the insect to a light may be true 

 enough, but that the insect can be so attracted is perfectly true, 

 as is shown by the following letter which I received lately from 

 one of my brothers, who has lived for some years in Brazil, and 

 has always taken great interest in entomology : — 



" There was a very strange case of the attraction of light for 

 some species of insects. On Tuesday last, a Brazilian gentleman 

 was with me looking out of the doer after dark, and we saw a 

 very bright light some five hundred yards off. It was moving 

 about the trees on the side of a high hill that rises from the side 

 of the river. 



" After watching it for some time, my friend said that it was a 

 ' vagalume' and that if I put a light out at the door it would 

 come to it. So, though rather unbelieving, I brought out a lamp, 

 and, sure enough, the light, instead of continuing among the. 

 trees on the other side of the river, came straight to the lamp, 

 and not two minutes from the time that I brought out the lamp 



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