LIFE-HISTORY OF THE NEW ZEALAND GLOW-WOEM. 27 



Staphylinidae (Coleoptera), and carnivorous. The light he con- 

 sidered attracted, and the web entangled, minute insects on which 

 he supposed the larva to feed. It will be seen that his supposition 

 as to the nature of the insect is entirely contradicted by subse- 

 quent investigation, whilst the latter conjecture has not in any 

 way been corroborated, as we are still entirely in the dark as to 

 the use of either the web or the light to the larva. 



During February and March, 1886, I instituted very careful 

 observations on the larvae, keeping several specimens in captivity. 

 From these I ascertained that the light was not exhibited at all 

 regularly, sometimes being brightest at night and sometimes in 

 the early morning hours. I have since noticed that, in the 

 natural state, the larvae shine most brilliantly on dark, damp nights 

 with a light N.W. wind. 



The web referred to above is suspended in a rocky or earthy 

 niche in the banks of a stream, in the densest parts of the forest. 

 It consists of a thick glutinous thread stretched across the niche, 

 and supported by several smaller threads running right and left, 

 and attached to the sides and end of the cavity. On this the 

 larva invariably rests, but, when disturbed, immediately glides 

 back along the main thread, and retreats into a hole which it has 

 provided at the end of it. From the lower side of this central 

 thread numerous smaller threads hang down, and are always 

 covered with little globules of water, resembling a number of 

 minute silver-beaded necklaces, constituting a conspicuous — 

 though apparently unimportant — portion of the insect's web. It 

 should be mentioned that all these threads are constructed by 

 the larva from a sticky mucus exuded from the mouth. 



The organ which emits the light is situated at the posterior 

 extremity of the larva, and is a gelatinous and semi-transparent 

 structure, capable of a great diversity of form. It can be withdrawn 

 or extended at the will of the larva, which, however, can immedi- 

 ately cease to shine without withdrawing it. This action is most 

 likely effected by shutting off the air from the tracheae ramifying 

 through the "light organ," which being, no doubt, largely com- 

 posed of phosphorus only, becomes luminous when in contact with 

 the oxygen in the air-tubes. Larvae cease to shine on very cold 

 nights, in the daytime, and in a room which is artificially lighted. 



During my observations in 1886 one of the larvae disappeared, 

 and I naturally assumed that it had buried itself in the earth, 

 and was undergoing its transformation into the pupa state. This 

 was apparently confirmed by the emergence, in about a month's 

 time, of a fly, which was afterwards identified by Baron Oaten- 

 Sacken as Trimiera pilipes, the larva of which is well known and 

 has nothing to do with the present insect. It is most unfortunate 

 that a larva of this Trimiera should have got into the breeding- 

 cage without my knowing it, and thus deceived me, 



