504 LUMINOUS INSECTS. 
beetle, from which it is altogether so different that nothing but actual 
observation could have inferred the fact of their being the sexes of the 
same insect. In the course of our inquiries you will find that sexual dif. 
ferences even more extraordinary exist in the insect world. 
Tt has been supposed by many that the males of the different species of 
Lampyris do not possess the property of giving out any light; but it is now 
ascertained that this supposition is inaccurate, though their light is much 
less vivid than that of the female. Ray first pointed out this fact with 
respect to L, noctiluca', which has two luminous points on the penultimate 
abdominal segment. In the males of L. splendidula and of I., hemiptera the 
light is very distinct, and may be seen in the former while flying.? The 
females, like the males, have the same faculty of extinguishing or concealing 
their light—a very necessary provision to guard them from the attacks of 
nocturnal birds ; Mr. White even thinks that they regularly put it out be- 
tween eleven and twelve every night °; and they have also the power of 
rendering it for a while more vivid than ordinary. 
Authors who have noticed the luminous parts of the common female 
glow-worm having usually contented themselves with stating that the light 
issues from the three last ventral segments of the abdomen‘, I shall give 
you the result of some observations I once made upon this subject. One 
evening, in the beginning of July, meeting with two of these insects, I 
placed them on my hand. At first their light was exceedingly brilliant, so 
as to appear even at the junctions of the upper or dorsal segments of the 
abdomen. Soon after I had taken them, one withdrew its light altogether, 
but the other continued to shine. While it did this it was laid upon its 
back, the abdomen forming an angle with the rest of its body, and the last 
or anal segment being kept in constant motion. This segment was distin- 
guished by two round and very vivid spots of light; which, in the specimen 
that had ceased to shine, were the last that disappeared, and they seem to 
be the first parts that become luminous when the animal is disposed to 
yield its light. The penultimate and antepenultimate segments each ex- 
hibited a middle transverse band of yellow radiance, terminated towards 
the trunk by an obtusely-dentated line ; a greener and fainter light being 
emitted by the rest of the segment. 
Though many of the females of the Lampyride ave without wings, and 
even elytra (in which circumstance they differ from all other apterous Cole- 
optera), this is not the case with all. ‘The female of Pygolampis ° Italica, a 
species common in Italy, and which, if we may trust to the accuracy of the 
account given by Mr. Waller in the Philosophical Transactions for 1684, 
would seem to have been taken by him in Hertfordshire, is winged: and when 
a number of these moving stars are seen to dart through the air in a dark 
night, nothing can have a more beautiful effect. Sir J. E. Smith tells us 
that the beaux of Italy are accustomed in an evening to adorn the heads of 
the ladies with these artificial diamonds, by sticking them into their hair ; 
and a similar custom, as I have before informed you, prevails amongst the 
ladies of India, 
1 Hist. Ins. 81. % Illiger, Mag. iv. 195. 
3 Nat. Hist. ii, 279. 4 Geoffr. i. 167. De Geer, iv. 35. 
> I call by this name all those Zampyride whose head is not at all, or but 
Bie our aad by the shield of the prothorax, and both sexes of which are 
wing 
