108 PROTECTION OF PLANTS 1923-24 



the case in both sexes, beginning; from segments 6 or 7, the abdominal segments 

 being divided off by well marked sutural lines. These last support an armature 

 of large and small barded processes on the dorsal side, which assist the pupa 

 to reach the exterior. Each segment is divided into three areas, more or less 

 distinct, and arranged as follows : 



1. The first or anterior area, rather more thickly chitinized, has a row 

 of coarse, broad-pointea, spear-shaped spines across its posterior border and 

 is set with deep, rather coarse depressions. 



2. The second or median area of thinner chitin has a row of fine toothed 

 spines crossing its posterior border and a number of shallow elongated punctures, 

 somewhat scattered. 



3. The third or posterior area, a thin and narrow strip adjoining the me- 

 dian caudal border, is covered with a fine reticulation which likely provides 

 for any expansion or contraction of the case. 



The spines are placed transversely on the segments and point- away from 

 the head. Their arrangement is slightly aifferent in each sex, the male carrying 

 a row of finer spines on the 7th segment, whereas the female is without these. 

 In both sexes the large coarse teeth are fairly regular in outline. The larger 

 of these m each row are s'tuated mid-dorsally and taper off gradually as they 

 pass down, laterally, some distance beneath the spiracular line and in front of 

 the spiracle on all segments except the first three. In segment 1 the entire row 

 is absent; in 2 they terminate just above the spiracle; and in 3 they run to the 

 top of the spiracle. There is a gradual increase in size of the larger dentations 

 from 2 to 9 and also a corresponding irregularity ir their form. The spiracles 

 are large and quite prominent in both sexes, those of segment 8 being imperfect. 

 They are tureen-shaped with outer edges smooth and rounded. The basal in- 

 terior is lined with very fine bristles which when contracted pack together 

 like two hair brushes tightly closing the aperture. 



For a detailed study of the principal features of the external morphology 

 of the pupal case of Prionoxyotus macmurtrei, by the writer, see 54th Report of 

 Ontario Entomological Society, 1923. 



Pupation. 



Towards the end of September the larva begins to lay down a soft silk 

 covering over the floor and walls, at the farthest end of the tunnel which has 

 been gouged out and rounded smoothly like the bottom of a test-tube. Having 

 done this it turns about, head outwards, and starts to erect a thick, grey, fe't- 

 like curtain, at a point about two inches from the extreme end of the cell, spinning 

 this from the circumference inwards and finally closing same at the centre, 

 thereby completely shutting itself off from the rest of the passage. Here the 

 transformation occurs and winter is spent as a pupa. The following example 

 may be cited here to illustrate the above: An oak was felled on September 29, 

 1920, and on being cut open, a full grown larva was discovered in the process of 

 constructing its pupal bed. Fortunately, the log split in such a way as to show 

 the whole cell very well. The chamber which was neatly, but rather thinly 

 lined with silk had already been completed and the occupant was busy weaving 

 the felt door which was only half finished at the time it was disturbed. 



About the end of May or early in June, when ready to emerge, the pupa 

 breaks through the felt curtain at the cell entrance and by a number of con- 

 tractions and expansions of the abdomen it begins to move forward on its back 

 out of the pupal bed into the tunnel. In this manner it makes its way along the 



