M. Lacordaire,--an authority on South American insects second to none,
says that he himself indeed never saw a luminous _Fulgora_ all the time
he was collecting in Brazil and Cayenne, and that most of the
inhabitants of the latter country, when questioned on the subject,
denied the fact, yet _that others of the natives as distinctly affirmed
that it is luminous_. He asks whether it is not possible that the light
may be confined to one sex, and thus the conflicting testimony be
reconciled; and gives it as his opinion that the point is rather one
which requires more careful observation, than one which we can consider
absolutely decided.[150]

Again, the Marquis Spinola, in an elaborate paper on this tribe,
published in the Annals of the Entomological Society of France,[151]
strenuously contends that the remarkable development of the frontal
portion of the head in the whole race is luminous. And finally, a friend
of Mr Wesmael assured him that he had himself seen the American
_Fulgora_ luminous while alive.[152]

It may help to sustain our faith in the veracity of Madame Merian, to
know that there is some reason for attributing occasional luminosity to
well-known English insects, of which hundreds, and even thousands, have
been taken without manifesting a trace of the phenomenon. Mr Spence, in
his interesting Letter on Luminous Insects,[153] adduces the following
evidence:--Insects "may be luminous which have not hitherto been
suspected of being so. This seems proved by the following fact: A
learned friend has informed me, that when he was curate of Ickleton,
Cambridgeshire, in 1780, a farmer of that place, of the name of
Simpringham, brought to him a mole-cricket (_Gryllotalpa vulgaris_,
Latr.), and told him that one of his people seeing a _Jack-o'-lantern_,
pursued it, and knocked it down, when it proved to be this insect, and
the identical specimen shewn 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 _ignes
fatui_, and to shew 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 globes seen by Dr Shaw cannot be thus