avoid; at least I have never known an instance where a larva has allowed its tunnel to communicate with another one, whether inhabited or otherwise. The caterpillar, when full grown, measures from 2½ to 3 inches in length. It is tolerably uniform in thickness, and of a dull yellow colour. The head is large, dark brown, very irregularly striated, and covered with a few short bristles. The first segment is hard and shining with the back and sides ruddy-brown. Its spiracle, which is very large, is situated near the posterior margin, and a little above it there is a dull black spot, filling a slight concavity about the same size as the spiracle itself. Each remaining segment has on its dorsal surface two horny plates, and two similar plates are situated on each side immediately below the spiracle. The body of the larva is thinly covered with yellow and black bristles. In many specimens the ventral surface and connecting membrane between the horny plates is pale purple. Younger specimens differ in being of an olive-green colour, which is much more pronounced, when they are small. The last act performed by the caterpillar, prior to undergoing its transformation, is the construction of the above-described trap-door at the top of its burrow. This done the insect retreats to the bottom, its posterior segment resting on the termination of the vertical gallery. In the course of a few days the skin is cast off and worked downwards to the bottom of the burrow, underneath the last segment of the pupa. This pupa varies from 2 to 2½ inches in length. It is attenuated in form and pale reddish-yellow in colour. The head and dorsal portion of the thorax are dark brown and harder than the rest of the body. The edges of the abdominal segments are furnished dorsally with a row of small {131}hooklets above and below all the divisions; on the ventral surface there is only a single row, which is situated in front of each articulation. As development progresses in the pupa it becomes darker in colour, especially on the wing-cases, where, in some female specimens, the future black markings of the moth are quite discernible as long as two months before emergence. Other specimens remain pale in colour until within a fortnight or three weeks of the appearance of the imago, when the green colouring of the wings suddenly becomes visible through their semi-transparent envelopes. When about to emerge the pupa works its way up the vertical tunnel by means of the above-mentioned hooklets, forces open the trap-door, and wriggles along the horizontal burrow until it reaches the air, only the last three or four segments remaining in the tree. Its anterior portions then break open and the moth crawls out and expands its wings in the ordinary way, resting on the trunk of the tree, until they are of sufficient strength and hardness for flight.