122 NATURAL HISTORY. [cH. VII 



also in possession of this luminous property, but in 

 a less degree ; the light in it is only distinguishable 

 when the wings are expanded, or when the insects 

 are flying, as the luminous matter is hidden and 

 much smaller in this sex. 



The females of the glow-worm can occasionally 

 conceal or eclipse their light. The author of the 

 excellent " Natural History of Selborne" supposed 

 that they regularly extinguished the torch between 

 the hours of eleven and twelve ; which has called 

 forth the idea that it may be to secure themselves 

 from becoming the prey of the nightingale or some 

 other nocturnal bird : while the author of the " Jour- 

 nal of a Naturalist" considers that the summer light 

 of the glow-worm is displayed as a signal taper, or, 

 as Mr. Moore has more poetically said — 



" The glow-worm's lamp is gleaming, love." 



The appearance of the autumnal light can have no 

 such object, unless it serves as a point of union in 

 the supposed migrations, like the leading call_ in 

 migratory birds.* The last mentioned observer in- 

 forms us " that the light of the glow-worm has sen- 

 sibly diminished since the 14th of July. Though 

 deep in the herbage, a clear steady light has been 

 observed as late on one occasion as the 28th of Sep- 

 tember, J 826, though very different in its sparkling 

 from that of the summer months. The light of one, 

 if placed on the watch-glass, is sutTicient to ascer- 

 tain the hour: nor is it an uncommon occurrence 

 for anglers, &c., to place several of these insects on 

 their hats, when they have been out in the evening, 

 to cheer them after their day's sport. 



We are informed by Mr. Macartney that the light- 

 yielding matter reposes under the transparent por- 

 tion of the skin, through which it is seen ; and he 



* The common people of Italy believe that these insects in- 

 habit the graves of the departed. 



