74 



Notes on the Glov/-worm (Lampyris noctiluca). 



By R. A. R. Priskk, IvE.S., and H. Main, B.Sc, RE.S. Read 

 January 12///, igii. 



The glow-worm is probably a familiar object to all, as its bright 

 light on a warm evening in June or July is so frequently to be seen 

 in many parts of the country. 



If on a "sugaring" expedition we take advantage of our lantern 

 to turn its rays on the place where we have seen the light of one of 

 these insects, we shall be able to note that it is not resting flat on 

 the ground, but has climbed up some twig or stem, and is curving its 

 abdomen so that the light, which proceeds chiefly from the ventral 

 part of the sixth and seventh segments, can have an uninterrupted 

 course. This position can be seen in PI. VII, figs, i and 2, and also 

 the light area in the region of the luminous organ. This latter con- 

 sists of special cells well supplied with air-tubes and nerves, and the 

 light is caused by some substnnce secreted by these cells. 



Of course the glow-worm is not a worm at all, but the female of 

 the beetle Lampyris noctiluca. She is quite wingless, but the male 

 (PI. VII, figs. 3 and 4) has ample wings, and may often be found 

 attracted by light. 



The head of the male can be retracted below ihe thoracic plate, 

 but on commencing to walk the insect pushes it out, and it is then 

 seen to be occupied chiefly by the two large compound eyes (PI. VII, 

 figs. 5 and 6). The female can also withdraw her head below the 

 thoracic plate. Her eyes, however, occupy only a small area of the 

 head. 



The great brilliancy of the female, together with the large eyes of 

 the male, would lead one to conclude that the use of the light was 

 for the purpose of attracting the male. It has been suggested by 

 some naturalists that this is not the only use for the light, because 

 it is also found to a small extent in the male, and the ova, larvre, 

 and pupre are distinctly luminous ; but there are instances in other 

 animals of organs present ni the male and immature forms which 

 are only functional in the mature female. 



A number of glow-worms taken last July were kept in various 

 boxes, and eggs were laid freely by some of the insects. Only those 

 eggs, however, which were kept in a moist atmosphere survived, the 

 others soon shrivelling up. The eggs (PI. VIII, fig. i) were spherical, 

 and did nut appear to show any structural markings. Those laid in 

 the dry boxes adhered to the surface on which they rested, but those 



