JUNE. 205 



more familiar with them. Even now, if I see one suddenly, 

 without having expected it, the impression momentarily re- 

 curs. They more frequently give out the light while flying, 

 than when crawling or resting, though we may often observe 

 the intennittent gleam as one crawls up a stalk of grass, or 

 rests on the leaf of a tree. They fly slowly, and as they 

 fly, emit and conceal their light with great regularity at in- 

 tervals of two or three seconds : making interrupted lines of 

 light through the air, gleaming slowly along for about a yard, 

 then suddenly quenched, and appearing again at the same 

 distance a- head. The insect is a pretty beetle, with soft 

 elytra, of a light brown colour, marked with red, and hand- 

 somely striped : the light proceeds from the last three seg- 

 ments of the abdomen, which are of a delicate cream colour 

 by day. At night these three segments are bright at all 

 times, but at the regular intervals I have mentioned, they 

 flash out with dazzling splendour. If this part be plucked 

 off and crushed, many patches of brilliance occur for a few 

 moments among the flesh, but they gradually die away. In 

 summer evenings, they often occur in great numbers, espe- 

 cially over wet and marshy ground : I have seen the whole 

 air, for a few yards above the surface of a large field, com- 

 pletely filled with them, thicker than the stars on a winter 

 night ; and, flashing and disappearing, every one moving 

 about in their mazy evolutions, it is really a very beautiful 

 sight : it is commonly believed these numbers precede rain. 

 Notwithstanding their abundance, they are not often seen 

 by day. They are usually known here by the name of light- 

 ning bugs. 



C. — What can be the use of their light ? 



jP. — That it has some end useful in their economy may 

 not be doubted; but what that end is, we are entirely ignorant. 

 It has been concluded and taken for granted that, in a parallel 

 case, that of the common Glowworm of England (hampyris 



