24 LIFE HISTORY OF TIMBER Mf)THS. 



the opening', each species hiiving its own special way, some 

 cutting ott' and removing all traces of the protective web. The 

 kinds that do not bite away the original web first remove impedi- 

 ments between the hole and the web, then weaken it by gnawing 

 out a circular space almost through, and lastly simply spin a fine 

 silken network around the opening into the chamber, the pupa, 

 not the moth, forcing its way through inner and outer webs 

 when making the final change; whilst those that do remove it 

 form a strong operculum. Having finished these preparations, 

 in a few days the change takes place to the chrysalis, which is at 

 first very pale in colour, but gradually changes until in about a 

 month it assumes a pink hue, which again begins to turn until 

 all the beautiful tints of the imago make their appearance through 

 the thin diaphanous shell of the pupa. Having remained in the 

 pupal state for from six weeks to occasionally as long as three 

 months, the day arrives when it is to make its final transforma- 

 tion. For some days before it has been restless, rising up and 

 down in its chamber by alternately extending and contracting 

 the body segments. About an hour or so before sunset, generally 

 between 8 and /J o'clock, it finally forces itself through all its 

 bulwarks, until only the last few segments of the body remain in 

 the l)urrow, and thus form the fulcrum for the severe exertions 

 of a critical period of its existence, for should it come too far, 

 slip out and fall to the ground, as occasionally happens, it can 

 only wriggle about, and is (piite unable to effect its change. It 

 begins now to bend itself l)ack\vards and forwards with a curious 

 nodding motion until the integument over the back of the thorax 

 bursts asunder, continuing the motion until it frees its head and 

 legs, and bending over at right angles catches hold with its 

 hooked feet upon some part of the stem, when with a quivering 

 morion it pulls itself out of the pupa case, which is left sticking 

 out of the hole. Swinging round, it drops into position with 

 body hanging perpendicularly downward, its crumpled wings 

 projecting outwards ; these begin almost immediately to 

 expand. In about half-an-hour being fully expanded, they 

 are suddenly reflexed, and the moth then assumes a some- 

 what leaf-like aspect, remaining quiescent until just before dusk, 

 when its wings are sufficiently strong for flight. The flight of the 

 male is much stronger than that of the female, which being very 



