17 



thorax and a broad band along the dorsum are dark smoky-grey 

 with a greenish tinge, the lower portions of the larva are lighter, 

 with an ochreous tinge. The black tubercular spots are large and 

 very conspicuous. There are no skin markings whatever. The 

 caterpillar now turns over a large portion of a leaf, frequently the 

 whole of one side, parallel with the mid-rib. It is now very active 

 and, if disturbed, runs with great ease up or down the length of its 

 gallery, and, if the annoyance continues, will drop out on a thread 

 of silk. It eats the apex of its own leaf and portions of neighbour- 

 ing leaves, and in four or five days' time lies up for its last larval 

 change. 



This last usually occupies about forty-eight hours. After the 

 change the larva may have a black or a brown head ; the prothoracic 

 shield is ochreous and divided down the centre by a pale line ; the 

 body is of similar colour to that of the larva when in the fourth 

 stage but still darker. The larva at this period, the commencement 

 of the fifth stage, is darker than at any other time, but after a day 

 or two, as it begins to increase in size, so it gradually loses its 

 depth of colour until finally, just when fully grown, it becomes very 

 pale green. The black tubercular spots, however, remain strikingly 

 conspicuous. The larva measures about 18mm. and is quite stout. 

 It hides itself by day in a dwelling made by folding- over a lobe or 

 the whole apex of a leaf and fastening this with silken thread to the 

 portion adjoining. Occasionally the caterpillars will live between 

 two leaves spun together, but I have never found T. viridana larvae 

 in rolled leaves. I have found a great many leaves on oaks rolled 

 up from the apex at right angles to the mid-rib, but these invariably 

 contauied the larva of Cacoecia xylosteana. The larva remains in 

 the fifth stage for seven or eight days, and it is during this period 

 that most of the damage is done to the oak leaves. The larva 

 reaches this stage about the third week in May, when the leaves are 

 green and still tender, but of nearly their normal size. The apical 

 portions of the leaves are especially attacked and all but the mid-rib 

 and the stouter lateral ribs are eaten. Less advanced leaves often 

 found on the terminal shoots at this time are entirely consumed. 

 When full-grown the larva, which has now become quite plump, 

 prepares for the pupal change. In most cases it secretes itself in 

 its last dwelling, but when the foliage has been too severely damaged 

 to afford shelter the caterpillars will move to any neighbouring 

 plant and spin up in leaves even of a kind on which they would 

 probably not have fed. The white silken cocoons vary in toughness, 

 some larvffi being content with a slight lining to their dwellings, 

 while others use a much greater quantity of silk. 



The pupa remains in the cocoon from two to three weeks. When 

 the moth is ready for emergence the pupa case is thrust through the 

 cocoon, usually as far as the fourth or fifth abdominal segment, and 

 the moth, after freeing itself from the case, clings to it or to the 

 leaf while it expands its wings. When this operation is complete, 



