4.29 LUMINOUS INSECTS. 
him a mole-cricket (Gryllotalpa vulgaris, Latr.), and 
told him that one of his people, seeing a Jack-olantern, 
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, at least, partial 
explanation of the very obscure subject of zgnes fatuz, 
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 common 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 ex- 
plosions of phosphuretted hydrogene, as has been sug- 
gested by some, which must necessarily have been mo- 
mentary. But that the zgnis fatuus mentioned by Der- 
ham as haying 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 iends 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 forward 
* Travels, 2d Ed, 334, > Phil. Trans. 1729. 204. 
