422 LUMINOUS INSECTS. 



pursued it and knocked it down, when it proved to be 

 this insect, and the identical specimen shown to him. 



This singular fact, while it renders it probable that 

 some insects are luminous which no one has imagined 

 to be so, seems to afford a clue to the partial explana- 

 tion, at least, of the very obscure subject o^ignes fatui, 

 and to show that there is considerable ground for the 

 opinion long ago maintained by Ray and Willughby, 

 that the majority of these supposed meteors are no 

 other than luminous insects. That the large varying 

 lambent flames, mentioned by Beccaria to be very com- 

 mon in some parts of Italy, and the luminous globe seen 

 by Dr. Shaw^ cannot be thus explained, is obvious. 

 These were probably electrical phenomena: certainly 

 not explosions of phosphorated hydrogene, as has been 

 suggested by some, which must necessarily have been 

 momentary. But that the ignis fatiivs mentioned by 

 Derham as having been seen by himself, and which he 

 describes as flitting about a thistle'', was, though he 

 seems of a different opinion, no other than some lumi- 

 nous insect, I have little doubt. Mr. Sheppard informs 

 me that, travelling one night between Stamford and 

 Grantham on the top of the stage, he observed for 

 more than ten minutes a very large ignis fatuus in the 

 low marshy grounds, which had every appearance of 

 being an insect. The wind was very high : consequently, 

 had it been a vapour, it must have been carried for- 

 ward in a direct line ; but this was not the case. It 

 had the same motions as a Tipula, flying upwards and 

 downwards, backwards and forwards, sometimes ap' 



" rraue^s,2d Ed. 334 " Phil. Trans. 1729, 204. 



