THE LEPIDOPTERA. 71 



the numerous scars which occur at intervals on the trunks 

 of nearly all the trees. Three large tunnels open into this 

 shallow cavity : one in the centre, which runs right into the 

 middle of the stem, and one on each side, which run right 

 and left just under the bark. These are usually very short, 

 but sometimes extend half-way round the tree, and occa- 

 sionally even join one another on the opposite side. The 

 central tunnel has a slightly upward direction for a short 

 distance inwards, which effectually prevents it from be- 

 coming flooded with water ; afterwards it pursues an almost 

 horizontal course until it reaches the centre of the tree 

 when it appears to suddenly terminate. This, however, is 

 not the case, for, if the gallery floor is carefully examined 

 a short distance before its apparent termination, a round 

 trap-door will be found, compactly constructed of very 

 hard, smooth silk, and corresponding so closely with the 

 surrounding portion of the tunnel that it almost escapes 

 detection. When this lid is lifted a long perpendicular shaft 

 is disclosed which runs down the middle of the tree to a 

 depth of 14 or 16 inches, and is about six lines in diameter. 

 At the bottom of this the elongated pupa (Fig. ib) sleeps 

 quietly and securely in an upright position, the old larval 

 skin forming a soft support for the terminal segment of the 

 pupa to rest on. The upper end of this vertical shaft is 

 lined with silk, which forms a framework on which the 

 trap-door rests when closed. The lid itself is of a larger 

 size than the orifice which it covers, and this makes it 

 extremely difficult, if not impossible, to force it from the 

 outside, whilst it fits down so closely to the aperture as not 

 to be readily lifted. The object of this most ingenious 

 contrivance is, in all probability, to prevent the ingress of 

 insects, large numbers of spiders, slugs, and various 

 Orthoptera being frequently found in both central and lateral 

 tunnels, but they are quite unable to pass the trap-door. The 

 galleries of different individual larvae are all wonderfully 



