36 THE SAX JOSE OE CHINESE SCAI.E. 



is almost as noticeable on young twigs as on fruit, and is of the greatest 

 service in facilitating the inspection of trees which have been subject 

 to possible contagion. The almost microscopic young scale might easily 

 elude the most careful search, but the strikiuo^ circliuor ringr makes it 

 a comparatively conspicuous object without the aid of a glass. 



If the tree survives the attack the infested wood eventually becomes 

 knotty and irregular, partly from the sapping of the juices by the insect 

 and also without doubt largely from the poisoning of the sap of the 

 cambium layer by the punctures of the insect, as indicated by the dis- 

 coloration. Young peach trees will ordinarily survive the scale only 

 two or three vears. Pears are sometimes killed outright . but orenerally 

 maintain a feeble, sicklv existence, makino- little or no o;rowth for a 

 somewhat longer period. 



FOOD PLANTS. 



The San Jose scale may attack almost any deciduous plant, including 

 fruits, ornamentals, and the various shade trees. Food-plant lists 

 were published in Bulletins 3 and 12 of this Bureau, and several sub- 

 sequent writers have given lists, with important additions. The most 

 careful investigation of the subject, relating particularly to ornamental 

 trees and shrubs, but also to fruit trees, as these are often planted for 

 ornament, was that conducted by the State entomologist of Connecti- 

 cut. ^Ir. VT. E. Britton. who sent out a circular letter to the entomol- 

 ogists and horticultural inspectors of the various States asking for 

 data under three headings, nameh: (1) Plants commonly infested; 

 (2) those occasionally or -rarely infested; (3) those not infested. 

 Forty-live replies were received, and from these and other records his 

 list was prepared. This list T have reproduced, together with his 

 following explanatory paragraphs.'^' 



List of Hardy Tkees, Shrubs, and Vixes. 



commonly t»r badly infrsted. 



Acacia Sf). Lintner, Felt^ X. Y.; 'Ahvootl, Va. 



Akehia sp. Felt, N. Y. 



Akehia qoumta Decaisnc. Ahvood, Va. 



Amelanchler canadeitMS Medic, and other species. Shad-bush, Jiineberry. Britton, 



Koehler, Conn.; Alwood, Va. 

 Citrus trifolidta Linn. Scott, Ga. ; Alwood, Va.; Gossard, Fla. 

 Cornus alha Linn. var. aihmca Lodd. Britton, Conn. 

 Cornus haikyi Coult & Evans. Goukl (in N. Y.) . 

 Ojinius sangn'mea \Ai\n. Britton, Conn. 



Cotoitea.sttrr iip.? Britton, Conn.; Lintner, Felt, X. Y.; Card, R. I. 

 Cotoneaster vulgaris J^incW. Alwood, Va. 



o Report of the Connecticut Agricultural Experiment Station, 1902, Part II, 2d 

 Report of the Entomologist, pp. 132-138. 



