FAUNE ENTOMOLOGIQUE DE L AUSTRALIE 35 



with the bore, which, after going i I/2 or 2 inches abiuptly turns upward, and, in a full 

 12 months after, the small caterpillar, when first found scarcely an inch in length, has grown to 

 over 3 inches long, and a big space has been bitten above and around the discharging hole, which 

 is ahvays kept well backed iip with borings etc. and the bore may now be 5 or 6 inches in length; 

 during the next 12 months a larger amount of work is proportionately done, the gallery is 

 continued to 8, 9 or 10 inches (rarely 12) and the caterpillar has grown to the proportions of a 6 

 or 7 inch long sausage, the bands, at first very dark purple, hâve now become light purplish pink. 



Pupation period approaching, the caterpillar cuts the bark almost through above the dischar- 

 ging hole, and for about the diameter of a florin; this usually drics and breaks avay, leaving 

 the hole clear. The discharging aperture is then opened and enlarged, so, soon after pupation, 

 the insect's présence is revealed by thèse two holes ; the cutting out and clearing the second hole 

 is undoubtedly to admit of the escape of water, which would run into the emerging hole during 

 any heavy rain, and it is essential that the pupa be kept free from moisture other than the sap of 

 the tree. After thèse preliminaries the larva retreats backward, spinning spidery and sticky 

 webs, attaching fragments of wood and bark thereto, across the horizontal portion of its burrow, 

 also smearing the sides with an oily damp-feeling substance which keeps the wood smooth and 

 doubtless prevents it from shrinking or cracking. (Thèse remarks, before and after apply par- 

 ticularly to X. Boisdiivalli but are applicable to several other large species). The threads cease 

 until the créature has nearly reached the end of the bore, when it spins a close thick, sticky 

 whitish-yellow web about one quarter of an inch in depth ; many drops of moisture cling to this 

 for a considérable time. Next to this web is constructed the « plug » or operculum of web and 

 wood scrapings, which is a splendid protection against most enemies. The larva is now closely 

 confined, there being just a little space between it and the » plug ». Some days clapse before 

 pupation takes place — one species in Acacias remains unchanged for weeks, so after closing 

 itself in for the pupal change that moth may not appear for 3 or 4 months. In time the operculum 

 becomes dry, hard and tough, and the web below almost shrivels away, but the web of several 

 species is spongy and retains its greasiness and moisture, coming away with the operculum when 

 that is pushed down. One large species of larva possesses an unusually large quantity of the 

 oïly matter and uses it freely in the bore and upon the web below the operculum, the oil has 

 a very strong odor which is perceptible several feet away from the bore; this same species 

 occasionally pupates in the Autumn, the moth then not emerging for 16 to 18 weeks. 



The moths usually émerge in about 8 weeks time, the pupa breaking or pushing down the 

 operculum with his headpiece or beak, there being ample room for this to fall away at the 

 bottom in the space below, opposite the lower and smaller hole. Ail species do not eut out this 

 space several merely cutting a sloping hole direct from the bore. Two species eut far below as 

 well as above the ûrst discharging hole, and make several others at convenient distances, some of 

 the older tunnelling serving for storage of waste material which is packed in very tighthy, but 

 thèse usually retreat to the upper workings to undergo pupation. 



No two species of pupal shells are alike; those from the Wattles {acacias) hâve the color of 



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