148 IIR. E. p. STEBBING ON THE 



developing-stage it ]ives and feeds upon these. Soon after this 

 change of position a further moult is gone through. Moulting 

 takes place as follows : — The skin becomes ruptured anteriorly 

 at a horizontal line of cleavage just above the insertion of the 

 antennae, the split extending to the first segment of the thorax 

 on either side. At the same time, from a central point in this 

 horizontal line of cleavage a further rupture occurs in a vertical 

 plane, the split reaching a median point in the posterior edge of 

 the metathorax dorsally (PL 16. fig. 8), and to the centre of the 

 COX8B of the anterior pair of legs ventrally (PI. 16. fig. 9). This 

 cleavage having taken place in the chitinous covering, the insect 

 crawls slowly out. Consequently, as a reference to fig. 9 will 

 show, on the under surface of the old discarded skin the black 

 empty leg and antennal cases are to be found. These cast skins 

 remain gummed by the sugary secretion to the twigs (PI. 16. 

 fig. 11), the insects moving off to fresh ones. 



When numerous, the young coccids collect in clusters round 

 the twigs, covering thickly the thinner barked ones (PI. 16. 

 fig. 10). They are also to be found at wounds on older and 

 thicker branches. When they first quit the leaves the scales are 

 about 3'12 mm. in length. Prom then onwards their growth 

 becomes more rapid, at least one more casting of the skin takes 

 place, and they mature toward the end of March or middle of 

 April. They change their position and walk about over the 

 trees more often as they begin to reach their full development. 

 It is after this last moult that they acquire the white powdery 

 covering, and if the insect is at all numerous the twigs and 

 branches will be seen to be closely encircled with serried white 

 masses, often for a length of 6-9 inches, of the coccids, giving 

 them the appearance of being encrusted with snow, the scales 

 lying one upon the other, often one tipped up at an angle and 

 resting upon a companion below as depicted in PI. 17. fig. 1 and 

 PI. 18, a. Each has its proboscis firmly imbedded in the cam- 

 bium layer, and spends its time sucking in the sap of the branch. 

 I have mentioned that the insects are active throughout life 

 and march about over the trees, and this habit is perhaps more 

 especially noticeable in their later stages of development, when 

 their whitening appearance renders them more conspicuous. 

 When mature, they are to be seen crawling down the trunks of 

 the Sal-trees, these latter being often thickly dotted with the 

 fat white scales. 



