INSECT ENEMIES OF WESTERN FORESTS 



51 



Other common scales infestino; western coniferous trees include the 



following : 



Species 

 Matsiwoccus fasciculensis Herbert- 

 Tourneyella pinicola Ferris (fig. 23) 



Pit i/sokcniic.s insif/iiicola Craw 



Phij.sokcrnics coiicolor Cole 



Phijsokermes color ad en sis Ckll 



Hosts 



Ponderosa and digger pines. 



Monterey pine and otlier pines in California. 



Monterey pine. 



White fir. 



Bine sprnce in Colorado. 



Asp'idiotus ehrhorni Cole Douglas fir and cypress in California. 



Ehrhor-nia cupressl Ehrh. (41) Monterey cypress. 



Xylococcus macrocarpac Cole Monterey cypress. 



Aonidia shastac Cole Bigtree in California. 



Some of the mealy- 

 bugs also attack for- 

 est trees. These are 

 small, sof t-boclied 

 bugs covered with a 

 white powdery wax. 

 They are represented 

 by Pseudococcus ry- 

 ani Coq. on cypress, 

 incense cedar, a n d 

 redwood, and P. se- 

 quoiae Cole on red- 

 wood. 



The foregoing is 

 only a very brief and 

 incomplete treatment 

 of the scales and re- 

 lated insects wdiich 

 may be found attack- 

 ing forest trees, since 

 the species attacking 

 various broadleaved 

 trees (4^) are too 

 numerous to mention 

 here. 



SPIDER MITES 



Another group of 

 small animals of sap- 

 sucking habits is 

 that of the spider 

 mites. Strictly 

 speaking, these are not insects, since they have bodies divided into 

 two segments instead of three and have four pairs of legs instead of 

 three. However, since they are so closely related to insects, and their 

 work is so similar, they are considered in this discussion. The dam- 

 age resulting from their natural habit of sucking the juices from 

 leaves and tender stems of various plants, including many orna- 

 mental, shade, and forest trees, is considerable. The leaves turn 

 yellow and drop, and the trees attacked are often seriously weakened, 

 rendering them susceptible to attack by tree-killing insects. This 



]''IGU1{E 23. — 'J'Ih' iiicuular pine 

 on iMonlerey pine Iwi 



A'alural size. 



l)inicolu) 



