36 THE SAN JOSE OR CHINESE SCALE. 
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 striking circling ring 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 b} 7 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 years. Pears are sometimes killed outright, but generally 
maintain a feeble, sickly existence, making little or no growth for a 
somewhat longer period. 
FOOD PLANTS. 
The San Jose scale ma}^ 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, Mr. W. 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, namely: (1) Plants commonly infested: 
(2) those occasionally or rarely infested; (3) those not infested. 
Forty-five replies were received, and from these and other records his 
list was prepared. This list I have reproduced, together with his 
following explanatory paragraphs/' 
List of Hardy Trees, Shrubs, and Vines. 
commonly ok badly infested. 
Acacia sp. Lintner, Felt, N. Y. ; Alwood, Vn. 
Ahhiasp. Felt, N. Y. 
AJcebia quinata Decaisne. Alwood, Va. 
Amelanchier canadensis Medic, and other species. Shad-bush, Juneberry, Britton, 
Kbehler, Conn.; Alwood, Va. 
Citrus trifoliata Linn. Scott, Ga:; Alwood, Va.; Gossard, Fla. 
Cornus alba Linn. var. sibirica Lodd. Britton, Conn. 
Cornus baileyi Coult & Evans. Gould (in X. Y.). 
Cornus sanguinea Linn. -Britton, Conn. 
Cotoneaster sp.? Britton, Conn.; Lintner, Felt, N. V.; Card, R. T. 
Cotoneaster vulgaris Lindl. Alw I, Va. 
aReporl of the Connecticul Agricultural Experiment station, L902, Part [I, 2d 
Report of the Entomologist, pp. 1:52-138. 
