A REVISION OF NORTH AMERICAN CHRYSOBOTHRINI 57 



(Cercocarpus alnifolius Rydb.) , mesquite (Prosopis juliflora (Swartz) 

 De Candolle), apple (Malus sp.), plum (Prwnus domestica L.), 

 Pacific plum (Prunus subcordata Benth.), sweet cherry (Prunus 

 avium L.), hollyleaf cherry (Prunus ilicifolia (Nutt.) Walpers), 

 apricot (Prunus armeniaca L.), sour cherry (Prunus cerasus L.), 

 Myrobalan plum (Prunus cerasifera Ehrh.), almond (Prunus com- 

 munis (L.) Fritsch), English laurel (Prunus laurocerasus L.), Japa- 

 nese weeping cherry (Prunus subhirtella var. ShidareMgan Hort.), 

 Japanese flowering cherry (Prunus serrulata Lindl.), peach 

 (Amygdalus persica L.), loquat (EHobotrya japonica Lindl.), coffee- 

 berry or cascara (Rhamnus purshiana De Candolle), hollyleaf buck- 

 thorn (Rhamnus crocea Nutt.), Christmasberry (Photinia serrulata 

 Lindl.), oso berry (Osmaronia cerasiformis (Torr. and Gray) 

 Greene), white alder (Alnus rhombifolia Nutt.), madroha (Arbutus 

 menziesii Pursh), blue gum (Eucalyptus globulus Labill.), Jim brush 

 (Ceanothus sorediatus Hook and Arn.), cultivated currant (Ribes 

 rubrum L.), chaparral pea (Pickeringia montana Nutt.), cultivated 

 rose (Rosa sp.), loganberry (Rubus loganobaccus Bailey), raphiolepis 

 (Raphiolepis japonica Sieb and Zucc), thorn (Crataegus carrierei 

 Vauv.), firethorn (Pyracantha cocoinea var. lalandii Dipp.), quince 

 (Cydonia, oblonga Mill.), trailing cotoneaster (Cotoneaster hori- 

 zontalis Decne.), and Chinese wistaria (Wistaria sinensis Sweet). 



This species shows considerable variation in coloration and in the 

 shape of the pronotum, the color on the upper surface of the body 

 varying from brownish black to a rather uniform coppery red. The 

 pronotum is usually widest near the apical angles, with the sides con- 

 verging posteriorly or parallel along the middle, whereas in some 

 examples it is widest at the middle, with the sides regularly rounded. 

 The sculpture on the elytra is more or less variable as to distinctness 

 of the costae and foveae, and in the reddish examples the cupreous 

 foveae are less distinct because they are of the same color as the 

 surface of the elytra. The median sulcus on the pronotum is usually 

 distinct, but occasionally it is only vaguely indicated. In most speci- 

 mens examined the prosternal lobe is broad and very short, but in a 

 few it is rather narrow and much longer. The dilation on the 

 anterior tibia of the male is slightly variable; usually it is slightly 

 narrowed toward the apex, but occasionally a specimen is found in 

 which the dilation is more arcuately rounded because the tibia is 

 more strongly narrowed toward the apex. The tip of the last visible 

 sternite of the female in the typical form is narrowly, semicircularly 

 emarginate, whereas in other material it varies to only vaguely 

 emarginate. The length is from 6.5 "to 11 mm. 



This is one of the worst enemies of newly planted deciduous trees 

 and shrubs on the Pacific slope and is known as the Pacific flatheaded 

 borer. Many newly planted trees and shrubs are killed the first year. 

 It is impossible to exterminate this insect since it attacks a great 

 many varieties of indigenous trees and shrubs, as well as introduced 

 plants. For an extensive account of its habits, the paper by Burke 

 and Boving (1929) should be consulted. 



Horn (1886) in his original description records the specimens from 

 the Sacramento Valley sent to him by L. E. Ricksecker as infesting 

 apple trees, and also others collected in Owen's Valley. Chamberlin 

 (1926) gives the type locality as Owen's Valley, but the specimens in 



