SUPPOSED USE OF THE LIGHT 139 



part, is uppermost, thus making the light visible 

 from the air above. In thick hedges I often find the 

 light four or even five feet above the ground. Occa- 

 sionally a glow-worm will shine from a flat surface, 

 usually a big leaf on to which it has crawled when 

 climbing. Resting horizontally on the leaf, it curls its 

 abdomen up and over its body after the manner of the 

 earwig, until the light is in the right position. 



When we consider these facts the way in which 

 the body is curved and twisted about in order (as 

 it seems) to exhibit the light to an insect flying 

 through the air above, and the increase in the light 

 when the sexual excitement is at its greatest the 

 conclusion seems unavoidable that the light has an 

 important use, namely, to attract the male. Unavoid- 

 able, I say, and yet I am not wholly convinced. The 

 fire-flies of diurnal habits may be seen flying about, 

 feeding and pairing, by day; yet when evening comes 

 they fly abroad again, exhibiting their light. What 

 the function of the light is, or of what advantage it 

 is to the insect, we do not know. Again, it has seemed 

 to me that the male of the glow-worm, even when 

 attracted to the female, fears the light. Thus, when 

 the excitement of the shining glow-worm has caused 

 me to look for the male, I have found him, not indeed 

 in but outside of the circle of light, keeping close to 

 its borders, moving about on feet and wings in the 

 dark herbage and on the ground. I know very well 

 that not a few observations made by one person, but 



