in the Larva State, upon the Wood of Trees. 



469 



pupa : it follows from all these conditions, that a larva must either gnaw to 

 the surface, or very nearly to it ; or that no imago can come forth to the light 

 and air from the larva. It is found that larvae do this ; and the questions on 

 their instincts with which one may, consequently, instruct oneself, are : How 

 does the larva, when in a tree of considerable diameter, discover the direc- 

 tion of the circumference ? and how can it lengthen, as would seem to be 

 necessary on some occasions, the natural period of its course of eating ? 



Mr. Mathews, in the communication cited above, has enquired whether the 

 larva undergoes its changes in the tree, and in what manner the imago extri- 

 cates itself: he has added, " It appeared to me that the cavity at and near 

 the entrance (a) (inj^. 76.) was much too small for the exit of the insect 

 in either the larva or imago state," On this matter the following remarks 

 were subsequently conti'ibuted, and have not been previously published. 



" Lepidopterous insects [which are also antliate ones] whose larvae feed 

 on timber, had they no means of extrication after their metamorphosis except 

 through the original small aperture, must remain captive till they died. When 

 the larva has approached maturity, it will weaken the bark ; and sometimes 

 perforate it, filling up the outlet with dung, or some temporary door. Even 

 mandibulate insects [those that, in the imago state, have mandibles to prehend 

 and divide their food with] are, in their pupa state, generally found near the 

 surface of the bodies which have supported them ; .though, under particular 

 circumstances, they have been known to eat their way to liberty through a 

 sheet of lead." — [Lansdown Gidlding. St. Vincent, May 1. 1830.] 



The author of the preceding paragraph, except the parts of it that are en- 

 closed in crotchets, was a distinguished naturalist. It is pleasing to learn, on 

 such valid authority, that some insects in the larva state have the wonderful 

 instinct to make provision for their convenience in the imago one. The idea 

 of the larva filling the outlet with dung, appears to me objectionable ; and, as 

 one may assume, that it could only obtain this material from behind itself, 

 either this idea, or my previously expressed one, that a larva cannot turn 

 round in the channel it has gnawed, must be given up. 



Imago, (/g. 73. 6.) Wings of the male, 2-^ in. ; of the female, 2|. in. to 

 2f in.; somewhat naked, and translucent; snow white, with the veins and 

 upper edge yellowish ; thickly scattered over with numerous bluish black spots. 

 Spots upon the second pair of wings fainter ; fewer, except on the margins ; 

 none at the inner angle. Thorax white, except 12 black spots. It appears 

 in July, and lays its eggs during July or August. It is rather rare. (Chiefly 

 Rennie's Conspectus.^ 



Z)o'rCUS PARALLELOPI'pEDUS Stephens: SiNODe'nDRON CYLl'NDRIi 



jig.ll.; a, male; 6, female; <?, larva. The cum Fahricius : fig. 78.; a, 



parallelopipedal, or small. Stag Beetle. female ; b, male. The sub- 



cylindrical Sinodendrum. 



