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. 



It 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 1 , which has two luminous points on the penultimate 

 abdominal segment. In the males of L. splendidula and of //. hemiptera the 

 light is very distinct, and may be seen in the former while flying. 2 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 3 ; 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 4 , 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 Lampyridce are 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 5 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^ 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. 



i Hist. Ins. 81. 2 Illiger, Mag. iv. 195. 



5 Nat. Hist. ii. 279. 4 Geoffr. i. 167. De Geer, iv. 35. 



5 I call by this name all those Lampyridce whose head is not at all, or but 

 little, concealed by the shield of the prothorax, and both sexes of which are 

 winged. 



