294 DAVEXPOKT ACADEMY OF NATURAL SCIEXGE8. 



HISTOKY. 



The earliest account of this species I have been able to liiid, is that 

 of Dr. S. S. Rathvon above referred to. Dr. Rathvon first observed it 

 on the linden trees in Lancaster, Pa., several years previous to the pub- 

 lication of his paper in 1854. Besides the linden, he found them later 

 on the silver maple, grape vines and in one instance each, on a 

 wild rose bush, and on a beech. He goes on to say : '•'■ The ' silver-leaved 

 maple' (Acer dasycarpum) seems to be the greatest sufferer, and there 

 is not a doubt of the partiality of the insect for that particular tree, al- 

 though they are also found on others when standing near them." The 

 following is the description given by Dr. Rathvon : 



"The female is a brownish yellow on the back until all the eicgs are deposited when she 

 dies, and turns to a darker color, and resembles what is known in common language as a 

 •scab." Beneath, the female is of a dirty bluish white, without any appearance of feet, and 

 adhering closely to the bark of the smaller branches of trees by a simple anterior process, 

 which I have not yet been able to discover. The posterior portion of the body of the femalc 

 is free, to which is attached a " globular mass " of white, very elastic cotton-like fibre, which 

 serves as a shield or protection to the egtrs. The eggs are white, or yellowish white, in shape 

 similar to a common hen's egg, and so minute as to be scarcely perceptible to the naked 

 eye. The youui, immediately after exclusion, are also very minute, yellowish white, with a 

 brownish line down the middle of the body, legs and antennae white, nearly of equal length, 

 and the latter terminated by a seta or diverging hairs. The abdomen is terminated by two 

 very slender, white, hair-like appendages about two-thirds the length of the body : there are also 

 a few spiny hairs upon the legs and the anterior margin of the antennae, at the base of which 

 a;e the eyes which are black and distinct. They occur in such countless million.s that I pro- 

 pose to name the insect Coccus innmne 'abilis until a better or prior one may be found: — for 

 I have never .vet seen a description of them anywhere." 



The above description, together with the accompanying figure and re- 

 marks on habits, etc., applies so perfectly to the species which I have 

 studied, and is so much better than those given by later authors that I 

 do not hesitate to adopt the name proposed by Dr. Rathvon.* 



The next account of this insect is a brief article by the late Dr. Asa 

 Fitch, entitled " Rmxiges of Insects on Forest and Fruit Trees— Rem- 

 ed.v." inserted in the Transactions of New York State Agricultural 

 Society for lSo9, (Vol. XIX, pp. 775-776), but dated June •27, i860. The 

 description is very general, and partly erroneous, but is sufficient to 

 show that it should be placed in the modern genus Pulvinaria. It Is 

 said to be a ■' very extensive depredator upon the trees in Albany," also 

 " abundant upon the maples, especially the soft maples, at Rochester," 

 and •• in former years, I have occasionally met with single soecimens of 

 this scale on the trees here in Washington county." As it seems im- 

 probable that there should be more than one species of Pulvinaria on 

 the soft maple in this country. I think we may safely regard Fitch's 

 acericorticis as identical with Rathvon's inmoneralnlis and Walsh & 

 Biley's acericola. 



In 1862, in the pamphlet above referred to. Prof. Joseph Leidy men- 

 tions this insect as occurring on the silver maple in Philadelphia. He 



* In deciding upon the adoption of this name I have been aided by the good advice of Dr, 

 H. A. Hagen regarding the synonymy. 



