386 Jyisect Pests. 



THE OYSTER-SHELL BARK LOUSE. 



{Aspidiotus osfreccfonnis. Curtis.) 



This scale insect or Coccid appears to have increased lately in 

 British plantations. During 1906 a very badly infested plum tree 

 was pointed out to me by Mr. Getting of Eoss in his plantations, 

 so badly encrusted that it was cut down and burnt. The photograph 

 shows the dense scurfy covering of these scales, completely enveloping 

 the branches. The scale was seen to have spread to some other trees 

 around, and these were treated with all due care. The same scale 

 was twice pointed out to me by growers in Worcestershire (1), and 

 the same wise drastic treatment followed. 



In Kent this insect occurs mainly in the Maidstone area and 

 around Sittingbourne ; Mr. P. Smith tells me it is of frequent occur- 

 rence in the plantations (2). Xewstead (3) records it as common 

 in Cheshire, and from Haslemere, Surrey, Lewisham-, Bearsted (Kent), 

 and Portarlington, in Ireland. He further says it is extremely 

 local, but where it occurs it is abundant and injurious. 



The immature scales are of different appearance to the mature 

 ones, being darker and more uniform. 



Life-Histoi;y and Habits. 



The scale covering the insect is often somewhat like a small 

 native oyster shell, but it is subject to enormous variation in shape ; 

 the young scale being almost round. The scale is flattened, smooth 

 in texture, but shows concentric markings ; slightly out of the centre 

 is a circular black spot. 



Older scales become more elongate and irregular, and are greyer 

 in colour, especially when they thickly encrust the trees. They 

 then produce a scurfy appearance, but when younger and round in 

 form, they are scarcely noticeable, owing to their approximating the 

 colour of the bark. 



At times they are so flattened against the bark that they look 

 almost like the rind. This was the case with the specimens sent 

 from Sittingbourne. 



The Oyster-shell Bark Louse attacks plums, apples, pears, apricots, 

 nectarines and peaches. It has also been recorded on currants by 

 Newstead (3). Green (3) found it on heather in Kent. Newstead 

 says it " increases but slowly," but at times it seems to do otherwise, 

 and trees are too frequently killed by it. It certainly spreads slowly, 



