4 BULLETIN 838, U. S. DEPARTMENT OF AGRICULTURE. 



The scale insect, besides being distributed on the incense cedar, has 

 now spread until it occurs on a large percentage of the cypress trees 

 and hedges in almost every locality about San Francisco Bay, par- 

 ticularly on the San Francisco Peninsula, in the Santa Clara and 

 Livermore Valleys, and north of the bay in Solano, Marin, and So- 

 noma Counties. It has been found in one locality, Riverside, in south- 

 ern California, where a great many trees are planted for windbreaks. 

 It is also to be found on Guadalupe Island, Mexico, as it was recently 

 taken from herbarium specimens of Guadalupe cypress collected on 

 this island. 



The accompanying map (fig. 1) indicates the localities in which 

 the cypress bark scale has been found to date, as well as the range 

 of incense cedar and Monterey cypress. There are many localities 

 within the range of cypress and incense cedar, which the writer 

 has not yet visited, in which the scale insect will probably be 

 found, when investigated. In all probability it eventually will infest 

 all planted cypresses unless radical measures of control are adopted. 



Since it has been found that the cypress bark scale can live on 

 Arizona cypress, it is possible that it may spread to that host in 

 Arizona and Mexico, or it may even be able to adapt itself to closely 

 related hosts and spread throughout the country. 



INJURY. ' 



Injury to the tree is caused by the myriads of insects which are 

 to be found in every crack and crevice of the trunk, branches, and 

 twigs, each sucking out the plant juice through its long thread-like 

 mouth parts. Under each scale may be found a small brown ring 

 in the cambium, showing the tissue killed by each individual. 



There is no secretion of honeydew, except for a small amount by 

 the young larvae, and only a slight formation of black sooty fungus 

 about these insects, but a secretion of white cottony wax pro- 

 truding from the bark crevices and covering the twigs gives abundant 

 evidence of their presence (PI. II). 



First a limb or two on an infested cypress turns yellow, then 

 red or brown, giving the tree (PI. Ill) a scraggy appearance. This 

 appearance often starts near the top of the tree and works down 

 toward the center, or perhaps spreads from one limb to the rest until 

 the whole tree is dead. Quite often the trees are dug up or felled 

 before this final stage is reached; others are left to mar the land- 

 scape until they rot and fall. 



In hedges, yellow and red spots appear, which increase finally 

 to large proportions, leaving wide gaps of dead material which 

 eventually destroy the beauty of whole hedges. One hedge in 

 Livermore, nearly a half mile long, was infested and dead or dying 



