December 1, 1894.] 



KNOWLEDGE. 



2G9 



associated with a living animal frame. The glow-worm is 

 by far the most important terrestrial animal in Great 

 Britain that manifests this phenomenon of " phospho- 

 rescence," though amongst marine animals, and amongst 

 terrestrial species belonging to warmer latitudes, the 

 phenomenon is of very much wider occurrence. In fact, 

 there are few classes of animals that do not contain 

 species which are, at some season or other, more or less 

 phosphorescent ; fishes, insects, myriapods, Crustacea, 

 moUusca, sea-squirts, worms, ccelenterates, starfishes, 

 infusoria, all include phosphorescent species. In fact, so 

 common is the phenomenon amongst marine organisms, 

 that apparently we have in it the chief source of light to 

 those creatures that live in the abysmal depths of the 

 ocean, where the light of the sun never penetrates. But 

 while the sea teems with glowing animals, they are not 

 nearly so numerous on land, and, as already mentioned, 

 the glow-worm is, in this country, practically the only 

 terrestrial phosphorescent species which is likely to attract 

 general attention, the few centipedes, worms. &c., that are 

 its only rivals, being far inferior to it in brilliancy. 



But it is not only as a phosphorescent being that the 

 glow-worm is remarkable. In a great variety of respects 

 it is abnormal, and these peculiarities we will now proceed 

 to recount. It may be a surprise to some of our readers 

 to be told that the glow-worm is a beetle, i.e., a member 

 of the order Coleoptera, to which also belong the blister 

 beetle, the bloody-nose beetle, the bombardier beetle, and 

 others that we have recently described. It is most nearly 

 related to that section of the order which includes the 

 well-known " soldiers and sailors," the reddish and bluish- 

 black, soft-bodied flying insects that are so common in 

 summer, not only in the woods and fields, but in the streets 

 of our towns as well. Usually it is not reckoned as 

 belonging to the same family as these creatures, but is 

 placed in a different one next to them. This family is 

 called J.ampijiiihi;, and the English glow-worm is known 

 as f.awpi/ns n<ictihoii. It is the only species of its genus 

 with which we ar^ favoured in Great Britain, and in fact 

 almost the only representative of the whole family, for only 

 one other species, belonging to a different genus, is known 

 as British, and that is a rare one, having been found only 

 in two localities, and in both cases in towns ; so that, for 

 all practical purposes, the glow-worm may be taken as our 

 one British representative of the family Lampijriila'. The 

 family, in fact, is characteristic of tropical rather than of 

 temperate latitudes. 



The family l.aiiijujridte is one of eight, which are dis- 

 tinguished by their soft and flexible skin, very different 

 from what is found in the majority of the beetle order, 

 which includes the hardest-skinned of all insects. This 

 soft-skinned section is called Malacodermata, in conse- 

 quence of this peculiarity. It is curious that these 

 malacoderms, notwithstanding their soft and yielding skin, 

 are yet fiercely carnivorous. It is pretty easy to recognize 

 a beetle of this section by its very soft body, which often 

 has fleshy protuberances at the side, and its flexible wing- 

 covers, which are more or less delicately hairy, and some- 

 times become slightly distorted by bending and shrivelling 

 when the insect is dead. 8ome of the species are 

 exceedingly beautiful, being bright scarlet, or brilliant 

 metallic green, or exhibitmg combinations of the two. 

 The glow-worm has no such brilliancy of natural colour 

 to recommend it, but makes up for this deficiency by the 

 soft beauty of the greenish glow that appears in its 

 abdomen in the dark. 



The sexes of the glow-worm are so different that it will 

 be necessary to describe each separately, and we will take 

 the female first, as it is the more familiar. The appearance 



of the female glow-worm is so different from that of adult 

 insects generally, that it is difficult to believe in its maturity, 

 and still more in its being a beetle ; in fact, its coleopterous 

 nature would not easily be demonstrable were it not for 

 the appearance of the male. The female (Fig. 1) is an 

 absolutely wingless, grub-like creature, with a small head, 

 which is completely concealed beneath 

 a semicircular projecting scale, repre- 

 senting the dorsal part of the pro- 

 thorax of an ordinary insect. Behind 

 this scale are ten segments, all except 

 the first and last similar in form, and 

 each broadest behind, so that the edges 

 of the body become saw-like, with ten 

 notches. The first of the ten segments, 

 representing the mesothorax, is more 

 rounded than succeeding ones, and the 

 terminal one, like the prothorax, is 

 semicircular. The colour is blackish- 

 brown above, with the margins of all 

 the segments, and some patches in 

 the first two, more or less yellowish 

 whole surface is rough, and covered 

 Above, the insect is 



Fig. 1. — Fenialo 

 Glow-worm, niaguifietl 

 two diameters. 



the outer angles ot 

 or reddish. The 

 with extremely short silky hairs, 

 flat, the dorsal layer of each segment forming a sort of 

 shield projecting at the sides beyond the parts beneath, 

 though not to so great an extent as the semicircular 

 shield which covers the fore part. Each of these 

 trapezoidal shields has a slight ridge down the middle. 

 The under surface is very different, being convex and paler 

 in colour ; the last three segments are almost white, and 

 it is in these that the glow appears. Three pairs of short 

 legs are carried by the three thoracic segments, and the 

 head bears the usual pair of compound eyes, which are of 

 moderate size, and a pair of short antennae. As the insect 

 walks, its abdomen trails along the ground, the legs being 

 too far forward and too short to enable it to be raised. 

 It will thus be seen that the insect looks very much like a 

 larva, the thoracic shield being the only characteristic that 

 conveys any other suggestion to a cursory glance. 



The female is the only member of the family to which 

 the name of glow-worm would popularly be applied. It is 

 usually to be met with in the summer months on grassy or 

 mossy banks, where it lies awaiting the advent of its mate, 

 and showing at night, on its under side, a greenish glow 

 which proceeds from two bright spots on the last segment, 

 and from the greater part of the two preceding ones. Of 

 course, therefore, the full brilliance of the light can only be 

 seen when the insect is lying on its back. When disturbed 

 it feigns death, curving its abdomen downwards, and bend- 

 ing up its legs. When left to itself, it is not, as can readily 

 be imagined, a very active creature, and will often remain 

 in the same spot for hours, or it may be days, together. In 

 the daylight, owing to the absence of the luminosity, it is 

 seldom noticed except by those who are familar with its 

 form. In country roads it is sometimes to be met with 

 crawling along near the foot of the hedge, or crossing from 

 one side of the road to the other, and it may also be found 

 underneath stones. 



The appearance of the male (Fig. 2) is entirely diflerent, 

 and it is rarely discovered in a similar way to its partner. 

 As it has the ordinary wings and wing-covers of a beetle, 

 there is no difficulty in recognizing it as such. But, at first 

 sight, it would not readily be connected with its mate, 

 because the body, wherein lies the chief resemblance, is 

 concealed by the closed wings ; but if the elytra and wings 

 are removed, the close resemblance between the two 

 insects is at once obvious. There is the same semicircular 

 shield in front, the same segmented and notched body, with 



