GLOW-WORM. 



637 



and yet, being also night-fliers, the females are des- 

 titute 1 of any light. But here the analogy will not 

 hold in both cases : in the moths the males are 

 furnished with beautifully feathered antennae, and so 

 long as we are ignorant of the uses of these organs, 

 it is not too much to assert that they may give to their 

 possessors powers of appreciation or senses which 

 those species which have simple antennae are desti- 

 tute of; and this is the case with the male glow-worm, 

 although in various popular works, lately published, 

 these organs are represented as much feathered as in 

 the moths. 



In the " Journal of a Naturalist" we find the gene- 

 rally received opinion endeavoured to.be supported 

 by the structure of the thorax of the male glow-worm, 

 which is so formed that when at rest no portion of his 

 eyes are visible ; but the head is margined with a 

 horny band or plate, under which the eyes are 

 situated, and which prevents all upward vision, as 

 well as greatly to impede the view of lateral ob- 

 jects ; so that by confining his view in his nightly 

 flight to what is before or beneath him, his search is 

 greatly facilitated. It is true that the structure of the 

 thorax of the female glow-worrn is similar to that of 

 the male ; but it is only when at rest that its position 

 is such as is described by the author of the " Journal." 

 The membrane which connects the head with the an- 

 terior cavity of the thorax is in these insects much more 

 pliant and extensile than in any other beetles with 

 which we arc acquainted ; so that when employed, the 

 head is as much exserted as in other beetles ; so that 

 when taken in conjunction with the large size of his 

 eyes, the male glow-worm possesses a greater field of 

 sight, owing to the flexibility of the membranous 

 neck, than most other beetles. But it has been fur- 

 ther objected, that the popular theory cannot be main- 

 tained ; first, because in the earlier stages of the exist- 

 ence of the female insect it is slightly luminous* ; and, 

 secondly, that the males also possess in a small degree 

 the same power. The principle of gradual develop- 

 ment, however, is surely a sufficient answer to the 

 former objection, and we cannot see why the circum- 

 stance of the males being luminous should be a reason 

 why they should not be attracted by other lights ; 

 moreover, why should not the female be supposed to 

 possess a similar propensity of approaching luminous 

 objects as the male ? In some of the exotic species 

 the males are as luminous as the females, and the 

 latter furnished with wings ; and can it be supposec 

 that the latter would not be attracted either to a lamp 

 or to the light of the male ? 



The habits of the glow-worm have been recordec 

 by various authors ; the most interesting accounts 

 which we have met with are those given by Mr. Wil- 

 son, in his Entomologia Edinensis, by W. H. White 

 in the Magazine of Natural History for November 

 1835. The latter gentleman having collected some 

 females towards the end of June, confined them, with 

 a male, in a glass jar, with sand two inches deep a 



* It is evidently of the early and not the perfect state of th 

 insect of which the author of the " Journal of a Naturalist' 

 speaks, when recording their motions at the end of September 

 and which he regarded as indications of a migration to winter 

 quarters by the perfect insect, addinir, that " it we conclude tha 

 the summcr-light of the glow-worm is displayed as a signal taper 

 the appearance of this autumnal li^ht can have no such objec 

 in view, nor can we naturally assign any use of it to the crea 

 tute itself, unless, indeed, it serves as a point of union i 

 these supposed 1 migrations, like the leading-call in the fligh 

 of night-moving birds." 



he bottom, covered with moss, kept damp. After 

 arious experiments, he discovered a female half 

 uried in the shell of a nail (Helix nemoralis], in the 

 ct of feeding upon the inhabitant ; he accordingly 

 upplied his captives with snails, upon which they 

 hrove well, eating for the whole day without inter- 

 mission, after which they fasted for eight days. 

 About the middle of July he observed one of the 

 emales depositing her eggs amongst the moss ; 

 a week after which she died the remainder also died 

 t the beginning of the following month. " The 

 iggs," he proceeds, " were of a pale yellow colour 

 when deposited, and instantly emitted light ; and I 

 bund, when I had occasion to sprinkle the moss with 

 .vater, that the eggs emitted a stronger light ; they 

 jecame a little darker in four or five days. On 

 August 27th, the larva? began to appear. They were 

 rather lighter in colour than the eggs, but became 

 gradually darker as they advanced towards maturity. 

 They had, when young, the power of emitting light 

 or otherwise at pleasure. In sixteen days three of 

 the larva? ceased to eat (snails ?), and retired to one 

 side of the jar for the purpose of moulting or casting 

 their skins, in which operation they appeared to suffer 

 much ; they became very weak and languid, and 

 ceased to emit light. The operation being at length 

 overcome, two whole days passed before they ap- 

 peared to have strength to partake of food ; but after 

 they had once or twice taken nourishment, they be- 

 came more lively and vigorous, emitted a much 

 stronger light, and seemed to make amends for their 

 long fasting by eating, if I may so speak, with double 

 voracity. On the 10th of May following (making a 

 period of nearly nine months in coming to perfec- 

 tion) three of the larvae ceased to take food, and, 

 as I thought, to prepare for another moulting ; which 

 indeed was the case, but instead of a lively worm I 

 soon found (on the 13th) that one of them had be- 

 come a chrysalis, and the other two changed into the 

 same state on the 15th. The chrysalis, at first, ap- 

 peared of a yellowish colour, but soon deepened 

 into a reddish-brown. In the course of ten days 

 several other larva? entered into the chrysalis state ; 

 whilst others, to my great astonishment, still con- 

 tinued in their larva? state till the May following, 

 making a period of one year and nine months ; 

 whether this was owing to any improper treatment, 

 or whether they required longer time to arrive at 

 maturit3 r , a second experiment may be the means of 

 convincing me. But to return to my chrysalides ; 

 the first, a female, arrived at perfection on the 30th 

 of May ; the second, a male, on the 3rd of June, and 

 the third, a female, on the 5th. The skin of the chry- 

 salis is so transparent, that the perfect insect, whether 

 male or female, is easily distinguished through it." 



The larva of the glow-worm very much resembles 

 the perfect female in its form ; it may, however, be 

 distinguished by its larger size, and its colour, which 

 is velvety black, with the posterior angles of the seg- 

 ments dirty red, and by the rudimental structure of 

 its antenna? and legs ; the former, instead of being 

 composed of eleven joints, having only four ; and the 

 tarsi, instead of being five-jointed, consist of a single 

 short piece. The mandibles, on the contrary, are 

 much more developed in the larva? than in the per- 

 fect insect, being sickle-shaped, and very acute in the 

 former. The pupa resembles the perfect insect, ex- 

 cept that the limbs are laid along the breast, and 

 inclosed in a thin pellicle, the female pupa, of course, 



