THE GLOW-WORM. 135 



cases the light evidently cannot act as a guide. I am inclined 

 to believe that no utilitarian theory will account for this sin- 

 gular development of light from a living insect, and that the 

 phosphorescence was given to it for the same reason that the 

 butterfly's wing glows with many-coloured plumage, and the 

 rose is dowered with softly-tinted petals and sweet perfume. 



This insect is doubly interesting to the entomologist. In 

 the first place, it is a British light-producer ; and in the second, 

 its life in the larval state is a very valuable one to the agricul- 

 turist. It feeds on snails, attacking and devouring them while 

 still alive, their shells being no protection to the luckless mol 

 luscs. The structure of this larva is rather remarkable. In 

 ilie first place, it bears a singularly close resemblance to the 

 perfect female insect ; and in the next, it is furnished with a 

 peculiar apparatus at the end of tlie tail, which serves a double 

 purpose, primarily of assisting in locomotion, and secondarily 

 acting as a brush, by which the slime of the snail can be swept 

 from its body. In some works on entomology, this organ has 

 been erroneously drawn like a shaving-brush cut off square at 

 the end, whereas it consists of some seven or eight projections 

 from the end of the body, which can be protruded or with- 

 drawn at will. Almost as soon as the snails begin to come out 

 from the hiding-places in which they have lain dormant 

 through the winter, the Glow-worm larva is ready to attack 

 them, and thus plays its part in reducing the number of snails 

 that would have been produced by those which it kills, and so 

 helping to preserve the balance of Nature. 



It remains in the larval state until April or May, according 

 to the warmth of the weather, and then changes into a pupa, 

 <-he male and female forms being then very distinct, as the 

 former exhibits the rudiments of the elytra, while the latter 

 remains as wingless as in the larval state. After the lapse of 

 a fortnight or a little more, the pupal envelope bursts, and the 

 perfect Beetle makes its appearance. The generic name of 

 Larrvpyris is formed from two Greek words, signifying ' shinino^- 

 tail.' 



In the little Beetle known by the name oi Drilus flavescens. 

 we have another of the many unknown benefactors of tha 

 agriculturist and gardeners. A portrait of this insect is given 



