290 MAINS AGRICUIvTURAI, EXPERIMENT STATION. I9O9. 



ChermBS abietis Choi. 



This common European species has been variously designated 

 as "The Spruce Gall-louse"*, "The European Spruce Bud- 

 louse"t, "The Yellow Chermes"t, "The green-winged Chermes"** 

 and the gall has been aptly called the "pine-apple gall" on 

 account of its. form. 



This species has been for a good many years annually abund- 

 ant on the Norway and white spruces on the campus of the 

 University of Maine. I have collected the gall and the insect 

 at various stages frequently since the fall of 1903, without giving 

 the species any especial study except to compare my own obser- 

 vations with published accounts. 



Confusion in the literature of this species both in this country 

 and in Europe has existed on account of other species having 

 been confounded with it. Because of this it may not be out 

 of place to present my own notes, though probably containing 

 no new observations, in connection with the photographs of 

 the galls and the drawings of the species which they concern. 



The Gall. Fig. 137. The galls of abietis vary in size from 

 about i inch to i inch or more in length. They occur at the base 

 of terminal shoots and do not as a rule kill the twig. Where they 

 are numerous they cause serious deformations of the branches, 

 and small trees are sometimes ruined by their presence. Such 

 galls are not only very abundant on Norway spruces but they 

 are troublesome on the native white spruce in Maine. This 

 season (1909) a single white spruce 3 feet tall had more than 

 990 fresh galls upon it. The growing galls are green, with the 

 closed mouths of the cell marked by a A-shaped red line. The 

 shade pf this Une varies from purple to brick red in different 

 galls and at different times. The galls resemble in form a little 

 pine-apple, each section being represented by a needle much 

 enlarged at the base and Httle if at all at the tip. The rela- 

 tion of the galls to the twig on which they grow is shown in the 

 longitudinal sections in Figs. 138 and 139. It will be seen 

 that in some cases the gall entirely encircles the twig which 



*34th Report Mass. Agric. College. 



t Packard, sth Report of Ent. Comm. page 853. 



tDie Coniferen-Lause-Chermes. Prof. N. Cholodkovsky 1907 



** Me. Agric. Exp. Sta. Bui. 171. 



