INSECT ENEMIES OF WESTERN FORESTS 39 



CEDAR TWIG BEETLES 



Small twig- beetles belonging to the genus Phloeosinus are com- 

 monly found working in the twigs and limbs of cedarlike trees, 

 but they rarely are numerous enough to cause any appreciable 

 damage. In the limbs and twigs of California incense cedar are 

 found P. hoppingi Sw., P. antennatus Sw., P. fulgens Sw., and 

 P. vandykei Sw. In the twigs of Alaska yellow cedar P. keeni 

 Blkm. may be found. P. chamberlini Blkm. and P. hoppingi Sw. 

 work in the twigs of Sierra juniper in California and Oregon 

 while P. hoferi Blkm. attacks the twigs of various junipers in 

 Utah, Colorado, Wyoming, Texas, New Mexico, and Arizona. P. 

 spinosus Blkm. attacks Arizona cypress in Arizona and New 

 Mexico. 



In addition to breeding under the bark of twigs and branches, 

 adults of the larger species of Phloeosinus have the feeding habit 

 of nipping off the leaflets and of feeding by boring into the small 

 twigs of various cedars and cypresses. This injury is frequently 

 very severe in ornamentals and shade trees. 



Larger species of Phloeosinus attacking the main trunk of vari- 

 ous cedars, cypresses, and redwoods are discussed on page 167. 



OTHER TWIG BEETLES 



Most twig beetles attacking spruce and hemlock belong to the 

 genera Scolytus, Pityophthorus, Pseudohylesinus, Pityokteines, or 

 Ips. These are discussed on pages 163-166. 



Broadleaved trees are attacked by various bark beetles, includ- 

 ing many species of Micracinae. Many oak twig beetles belong to 

 the genus Pseudopityophthorus (p. 169) . 



The shrub bark beetle (Micracis hirtellus Lee.) is a secondary 

 species which mines the hard, dry wood of many flowering shrubs 

 and broadleaved trees including willow, alder, madrone, and Cali- 

 fornia laurel in California. The adults are dark reddish brown and 

 about y 8 inch long. They have been found boring into lead tele- 

 phone cables. 



TWIG WEEVILS 



Twig weevils, belonging to the family Curculionidae, often 

 cause serious damage to the terminals of young coniferous trees. 

 The adult female weevil uses her long, curved beak to excavate a 

 small pocket in the bark of the terminal shoot in which to place 

 her eggs. The young larvae, on hatching, burrow beneath the bark 

 and excavate winding tunnels between the bark and wood. On 

 reaching full growth each constructs an oval cell, partly in the 

 wood and partly in the bark, in which to pupate. Weevil work is 

 distinguished from that of the twig moths in that there is little 

 exudation of resin or pitch, and such as does occur is not mixed 

 with webbing or larval castings to indicate the presence of the 

 insects under the bark. The first conspicuous evidence of injury 

 is the dying of the terminal shoot. 



The three most important genera are Pissodes, Magdalis, and 

 Cylindrocopturus. In the East the white pine weevil (Pissodes 

 strobi (Peck)) is an important example of these insects. In the 



