Circular No. 121. Issued April 30, 1910. 
United States Department of Agriculture, 
BUREAU OF ENTOMOLOGY. 
L. O. HOWARD, Entomologist and Chief of Bureau. 
THE OYSTER-SHELL SCALE AND THE SCURFY SCALE. 
idosaphes ulmi L. and Ckionaspis/ur/ura Fitch.) 
By 
A L. Qi iiNTANi i , In i ha ■ ■ ous Fruit Insect 1 sligations, 
and 
E. R Sassceh - i lant. 
INTRODUCTION. 
The oyster-shel] scale (Lepidosaphes ulmi L.) and the scurfy scale 
(Chionaspis furfura Fitch) are, with the exception of the San Jose 
or Chinese scale (Aspidiotus pernidosus Comst.), more frequently the 
subject of inquiry by orchardists than all other species of scale insects 
combined. These two scale pests are now very generally distributed 
throughout the country, and from their relatively conspicuous appear- 
ance are often detected by observant fruit growers who frequently 
believe them to he the more serious San dose scale. The ovst er-shell 
and scurfy scales, while not dangerous in the sense of generally causing 
the death of infested trees, are, however, of considerable economic 
importance. The complete killing of individual branches of apple 
trees by either species is a matter of frequent observation, and trees 
so badly infested are frequently greatly stunted and retarded in their 
growth, resulting perhaps in extreme cases in the death of t he trees. 
Of the two species considered, the oyster-shell scale has been and is 
at the present time the more important. Its injuries to certain 
shade trees, especially poplar and maple, have been the cause of much 
complain t during recent years. Such shade trees are ordinarily not 
3prayed for scale insects, and the increase of these pests from year to 
year is thus checked only l>\ their natural enemies. The writers 
bave frequently seen maple and poplar trees literally incrusted from 
top t" bottom witli the oyster-shel] scale, manj "I' the limbs killed, 
and in rarer instances the trees quite dead — -without doubt owing to 
the at t ack of i his scale insect. 
[Clr. 121] 
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