DTT’ Stores,” 
UNITED STATES DEPARTMENT OF AGRICULTURE 
FARMERS 
BULLETIN 
WasHINnGtoNn, D.C. 650 Marcu 30, 1915 
Contribution from the Bureau of Entomology, L. O. Howard, Chief. 
THE SAN JOSE SCALE AND ITS CONTROL. 
By A. L. QUAINTANCE, 
In Charge of Deciduous Fruit Insect Investigations. 
CHARACTER OF INJURY. 
The San Jose or Chinese scale! infests practically all portions of 
its host plants that are above ground—the trunk, limbs, and 
branches—and when: abundant it may occur on the leaves and fruit. 
Injury results from the extraction, by the scale insects, of the juices 
of the plant. At first this merely checks growth, but as the insects 
increase in number the speedy killing of the branches and twigs 
follows, resulting finally in the death of the plants. In addition to 
the extraction, by the scales, of sap as food, the puncturing of the 
bark by the slender sucking mouth parts results in a diseased and 
often pitted condition; the inner bark, or cambium, shows a reddish 
discoloration, as exposed in cutting with a knife, and the bark itself 
may crack, in stone fruits exuding drops or masses of gum. A 
reddening effect is also much in evidence as red rings around the 
scales on the bark, especially of the apple and pear, and on the 
fruits of these plants, though not characteristic of any one scale 
species. 
On peach the scales have a tendency to infest to a greater extent 
the older limbs and branches than the newer growth, such as the wood 
1 year old. On apple and pear the terminal twigs are quite gen- 
erally infested, and many of the young may find their way to the 
fruit, settling principally in the calyx and stem cavities. Most 
varieties of fruit trees and plants infested from the nursery perhaps 
never reach fruiting condition unless treatment be given them. 
Peach trees will usually be killed in two or three seasons, while pear 
or apple trees will maintain a feeble existence much longer. 
1 Aspidiotus perniciosus Comstock; order Hemiptera, suborder Homoptera, family Coccide. 
80074°—Bull. 650—15——1 
