326 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 10 



Insect Investigations, Prof. E. C. Van Dyke of the University of Cali- 

 fornia and Prof. H. C. Fall of Pasadena, California. 



Dicerca prolongata Lee. — Specimens from South Dakota, Colorado, 

 Montana, Utah, Oregon and California; mines wood of injured, dying 

 and dead trees; willow (Salix sp.), aspen {Populus tremuloides) and 

 black Cottonwood (P. trichocarpa) ; flies from July to September; feeds 

 on bark of host plant; may attack planted poplars. 



Dicerca ohscura Fab. — What appears to be this common eastern 

 species has been taken at Chico, California, in the wood of the Oregon 

 ash {Fraxinus oregona); mines wood of injured, dying and dead trees; 

 the eastern host plants are white oak (Quercus alba Linn.) and per- 

 simmon {Diospyros virginiana) ; flies from April to September. May 

 become injurious to planted oak, ash and persimmon. 



Dicerca hornii Cr. — Montana, Idaho, Washington, Oregon and 

 California; mines wood of injured, dying and dead trees and shrubs; 

 white alder (Alntis rhomhifolia) , mountain alder (A. tenuifolia) , moun- 

 tain mahogany (Cercocarpus parvif alius), plum {Prunus domestica), 

 sweet cherrj^ (P. avium), sumach {Rhus glabra occidentalis) , poison oak 

 (Toxicodendron diver siloba), California buckeye {^sculus calif or nica), 

 coffee berry (Rhamnus calif ornica), deer brush (Ceanothus integerrimus) , 

 blue brush (C thyrsiflorus) , buck brush (C. cuneatus) and snow berry 

 {Syrnphoricarpos racemosus) ; flies from March to August; attacks 

 domestic plum and cherry and probably other fruit trees; causes severe 

 injury to the alder. 



Dicerca sp. close to divaricata Say — Montana and Colorado; mines 

 wood of dying and dead trees; mountain birch (Betula fontinalis), 

 mountain alder (Alnus tenuifolia), bitter cherry (Prunus emarginata) 

 and choke cherry (P. demissa); flies from July to September; may 

 attack planted birches and rosaceous fruit trees. 



Trachykele blondeli Mars. — Washington, Oregon and California; 

 mines wood of normal, injured, dying and dead trees; giant arbor vitse 

 (Thuja plicata), monterey cypress (Cupressus macrocarpa), McNab 

 cypress (C. macnahiana) and western juniper (Juniperus occidentalis) ; 

 flies from April to August; attacks planted cypress and probably other 

 planted cedarlike trees. 



Trachykele opulenta Fall — California; mines wood of normal, injured, 

 dying and dead trees; California bigtree (Sequoia washingtoniana) and 

 incense cedar (Libocedrus decurrens) ; flies April to June ; attacks planted 

 incense cedar and probably bigtree and redwood. 



Trachykele nimbosa Fall — Oregon and California; mines wood of 

 normal, injured, dying and dead trees; alpine hemlock (Tsuga merten- 

 siana), white fir (Abies concolor) and red fir (A. magnijica); flies during 

 June and July; may attack planted fir. 



