CYPRESS BARK SCALE. 6 



Stirling City and Giant Forest, Calif., by the writer. These localities 

 are all from 75 to 150 miles apart and from 5 to 50 miles distant from 

 any planted cypress. This seems to indicate that the incense cedar is 

 the native host for this scale insect. 



Mr. G. F. Ferris reports finding this scale insect upon herbarium 

 specimens of Guadalupe cypress (C. guaclalupensis) in the Stanford 

 University herbarium, collected on Guadalupe Island, Mexico. It is 

 impossible at present to state whether this is one of the native hosts 

 of the scale, or whether the scale has been carried there from the 

 mainland. 



DISTRIBUTION AND SPREAD. 



Incense cedar, the original host plant of the cypress bark scale, 

 occurs in California, Oregon, western Nevada, and Lower California. 

 The majority of these trees are found in the Sierra Nevada and 

 northern coast range mountains of California, and in the Siskiyou, 

 southern coast range, and Cascade Mountains of Oregon. 



The cypress bark scale has been found at four widely separated 

 points in the Sierra Nevadas (Stirling City, Placerville, Crockers, 

 and Giant Forest, Calif.) and at one point in the Siskiyou Mountains 

 (Ashland, Oreg.), which indicates that the scale undoubtedly occurs 

 throughout the major portion of the range of the original host. 



From this host the scale insect has spread to planted incense cedars 

 and cypresses in the more thickly populated regions of the State. 

 Two probable methods of distribution are suggested. 



The cypress bark scale has been found to thrive on very young 

 trees. Incense cedar seedlings occasionally are brought down from the 

 Sierra Nevadas by tourists to plant in their own yards, and it is quite 

 possible that the scale was carried to the valley on some of these 

 trees. Rustic incense cedar is also transported from the Sierra Ne- 

 vadas to be used quite extensively for pergolas and porch pillars- 

 Ordinarily this would be done during the summer, which is the re- 

 productive period for the scale insect. As the females can live for 

 some time on green logs, it would be very easy for the young larvae, 

 hatched en route or after the logs have reached their destination, to 

 attach themselves to near-by cypress trees, and thus start a heavy 

 infestation in a new location. 



From these original points of infestation the pest has spread 

 through large areas. This has been accomplished for short distances 

 by the usual agencies of wind, birds, insects, etc., and for longer dis- 

 tances by the shipment of infested nursery stock. The insect has been 

 found by the writer infesting cypress seedlings in nurseries. Close 

 planting of shade trees, hedges, and windbreaks undoubtedly aids in 

 its rapid spread by natural means. 



