CYPRESS BARK SCALE. t 



ASSOCIATED INSECTS. 



The cypress bark scale is by no means the only enemy of the 

 cypress. The cypress barkbeetles (Phloeo sinus cupressi Hopk. and 

 P. cristatus Lee.) are important primary insects, causing the death 

 of a considerable number of trees, and perhaps ranking first among 

 the pests of the cypress in California, considering the State as a 

 whole. In the San Francisco Bay region they must, however, take 

 a place second to the scale in point of damage done. 



Many people throughout the State have considered the beetles as 

 the only enemies of the cypress, and, when noting the death of a 

 tree, have taken it for granted that the beetles were the primary 

 cause, without bothering to investigate properly. The entire foliage 

 of trees killed by the beetles turns first yellow, then brown, and is 

 much more conspicuous than the foliage of a tree being killed by 

 inches by the scale insect. The presence of the beetles is also more 

 easily detected. 



At times the beetles have been found working independently of 

 other insects, and killing trees. For example, at San Carlos, on the 

 San Francisco Peninsula, the beetles have been killing several trees 

 per year for a number of years. In the spring of 1918 they were 

 found entering the green trunks of live trees and girdling them. 

 Other trees showing the work of Phloeosinus, dead one or two years, 

 stood near by. The recently attacked and the unattached trees were 

 apparently very healthy. 



The beetles are often secondary pests, entering trees well infested 

 and weakened by the scale insect. At Martinez, Calif., in January, 

 1918, a row of 12 trees was heavily infested with the scale insect. 

 Three of these had been recently killed by barkbeetles. On Alum 

 Eock Avenue, San Jose, Calif., there is a long double row of 

 cypresses, all of which are heavily infested with the cypress bark 

 scale and practically all of which have a sickly appearance. Here 

 the barkbeetles attack an occasional tree, or a section thereof, and 

 hasten its death. They also impair the beauty of the trees by 

 entering into the center of small twigs and weakening them, so that 

 the wind breaks them off. When gathered together, the twigs from 

 one tree formed a pile 2| feet high and nearly as broad. There 

 were also many twigs still hanging broken in the tree. The injury 

 to cypresses by these beetles will be treated separately in a later 

 paper. 



Three species of mealybugs, Pseudococcus ryani Coq., P. sequoias 

 (Coleman), and P. cupressicolus Ferris, also infest cypresses and 

 occasionally do some damage. 



Other associated scale insects are Xylococcus macrocarpae Cole- 

 man, Lecanium corni Bouche, Diaspis carueli Targ., Aspidiotus 



