The Cottony Maple Scale. 243 



THE COTTONY MAPLE SCALE. 

 (Pulvinaria iunumerabilis Rathvon.) 



By Harry Scott Smith. 



Owing to the prevalence of injury by this insect the following 

 paper is presented for publication: 



During the two years covered by this report, frequent complaints 

 have been received at the Entomologist's office concerning isolated 

 outbreaks of this extremely injurious and here in Nebraska our most 

 conspicuous pest of shade trees. Considering the usual abundance 

 of this insect in restricted localities throughout the state, it is thought 

 advisable to devote a few pages to a discussion of its character and 

 the best means of checking its ravages. 



The cottony maple scale is a pest native to the United States, 

 and one with which most persons are familiar by reason of its habit 

 of suddenly appearing in a locality where it was supposed to be entirely 

 absent, and the unsightly condition in which it leaves the trees after 

 infestation. It was first described in 1854 by Dr. S. S. Rathvon, of 

 Lancaster, Pa., and has since then been placed costantly before the 

 public eye in numerous bulletins and newspaper articles on account of 

 the damage it occasions in certain localities where conditions are es- 

 pecially favorable to its propagation. The most elaborate treatises 

 on this insect are those worked out by J. Duncan Putnam,* and more 

 recently by Dr. L. O. Howard.** 



This insect is of very general distribution, having been found In 

 greater or lesser numbers in almost every state in the Union. How- 

 ever, it rarely becomes injurious south of the fortieth parallel on 

 account of the great number of parasites which attack it in that 

 region.*** 



Here in Nebraska it occurs throughout the state, but, in accordance 

 with one of its chief characteristics, become injurious only occasionally 

 and usually in widely separated districts. The region of the greatest 



* Proceedings of the Davenport Academy of Natural Sciences, 

 Vol. II, 1879, pp., 293-347. 



**Bulletin No. 22, New Series, U. S. Dept. Agr. Div. Ent. pp. 7-16. 

 ***J. G. Sanders, Circular No. 64, Dept. Agr., Bureau of Ent. p. 2. 



