LUMINOUS INSECTS. 539 



the same insect. In the course of our inquu'ies you will find that sexual 

 differences 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 tlie female. Ray first pointed out this fact 

 with respect ioL. noctiluca^, which has two luminous points on the penul- 

 timate abdominal segment. In the males of L. splendiduJa and of L. 

 hemiptcra the light is very distinct, and may be seen in the former while 

 flying." The females, like the males, have the same faculty of extinguish- 

 ing 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 between 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 seg- 

 ment was distinguished 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 seg- 

 ments each exhibited a middle transverse band of yellow radiance, ter- 

 minated 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 Lampyridcc, are without wings, 

 and even elytra (in which circumstance they differ from all other apterous 

 Coleoptera), 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 Trans- 

 actions 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 beaus 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. 



Besides the different species of the genus Lampyris, all of which, to 

 the number of nearly two hundred, now divided into several distinct 

 genera, are probably more or less luminous, another insect of the beetle 



' Hist. Ins. 81. 2 Illiger, Mag. iv. 195. ^ j^^t. Hist. ii. 279. 



* Geoffr. i. 167. De Geer, iv. 35. 



* I call by this name all those Lampiridce whose head is not at all, or but little, concealed 

 by the shield of the prothorax, and both sexes of which are winged. 



