THE OYSTER-SHELL SCALE 



Lepidosaphes ulmi, L. 



By Franklin Sherman, Jr., Entomologist. 



Order Hemiptera. Family Coccidw. 



Introductory. The apple-growers of North Carolina complain more 

 often about the Oyster-shell Scale than they do of any other scale-insect 

 attacking their trees — with the exception of the San Jose Scale, which 

 still overshadows all others combined. It seldom kills the trees out- 

 right and therefore is not noticed so quickly as it deserves, and even 

 when trees are killed by it the grower usually never knows the real 

 cause. Hence the frequency of complaint of the Oyster-shell Scale is 

 not fully commensurate with the damage which it does. Probably the 

 greatest harm comes not so much from the few trees that are actually 

 killed, but from the general weakening and greater or less stunting effect 

 on the new growth of trees, which live on indefinitely but never attain 

 the full measure of health and productiveness that they would if this 

 scale were not present. 



It is primarily a pest of the apple tree, though many other kinds of 

 trees are more or less infested by it. It is not known to be present in 

 destructive numbers east of Raleigh, so a large part of the State is 

 seemingly (for the present at least) free from injury by it. To the 

 westward from Raleigh it is serious in scattered localities throughout 

 the middle section, and in the mountains it seems to be present in apple 

 orchards everywhere, though not often actually killing the trees. 



The most advanced growers, who give their trees spraying treatment 

 every year with sulphur or oil sprays as a precaution against San Jose 

 Scale and fungous diseases, appear to suffer but little from this Oyster- 

 shell Scale, because the strengths of these sulphur and oil sprays which 

 are used are sufficient to control this pest. But in small farm orchards 

 where no regular spraying is done this scale has free chance to multiply, 

 except for the natural enemies which prey upon it. For this reason 

 some knowledge of these natural enemies of the Oyster-shell Scale is of 

 interest and importance, r.nd in this account some attention is given to 

 this feature. 



A Well-known Pest. The Oyster-shell Scale is one of the best-known 

 and most widely-distributed of the scale-insects, and is mentioned in 

 almost every list of scale-insects and in bulletins on fruit insects from 

 all parts of the country, but it is most destructive in the northern states 

 and the higher, cooler parts of the southern states. Much of what is 

 known of it throughout America has been published in condensed form 

 as Circular ISTo. 121 of the Bureau of Entomology of the United States 

 Department of Agriculture, at Washington, D. C, written by A. L. 

 Quaintance and E. R. Sasscer. The account of it as given in this Bul- 

 letin is based not merely upon what others have already written (con- 

 firmed by our observations where possible), but also upon many observa- 

 tions and notes of our own and on the information gained from the 

 many complaints from citizens of the State. Considerable data has also 



