Contents: By Damage and Image
In progress
Contents: Alphabetical

alder flea beetle
aphid management
apple and thorn skeletonizer
apple ermine moth
ash whitefly
azalea bark scale
azalea lace bug
azalea sawfly
Bagrada bug
bark lice
Barypeithes root weevil
Beneficial nematodes
biocontrol of root weevils
birch aphid
black bean aphid
black cherry aphids
black stem borer
bluegum psyllid
Boisduval scale
branch and twig borer
brown marmorated stink bug

bronze birch borer
boxwood leafminer
boxwood psyllid
bulb flies
cabbage whitefly
carnation tortrix
carpet beetle (images)
Calligraph californica

Ceanothus stem gall moth
cereal leaf beetle
cherry ermine moth
chilli thrips
cinnabar moth
clay colored weevil
cottony camellia scale

crane flies
cypress tip moth

dogwood sawfly
Douglas fir sawfly
Douglas fir twig weevil
elm leafminer
European pine sawfly new
European pine shoot moth
European wool carder bee
emerald ash borer
Fall webworm
fir coneworm new
flatheaded cedar borer
ground beetle gallery
Hemerocallis gall midge new
hollyhock weevil
honeylocust plant bug
honeylocust pod gall midge
Heliothis phloxiphaga
holly bud moth
huckleberry root aphids
ground mealybug
Japanese beetle
lady beetle gallery
leaf weevil
light brown apple moth
Linden aphid new
lupine aphid new
Macrosiphum rhamni new
maple aphids
maple tip moth
maple midge
March flies
mountain ash sawfly
Myzocallis sp. on red oak new
Narcissus bulb fly
natural enemies gallery
oak ambrosia beetle
oak slug
oak twig gall wasp
obscure root weevil
Pacific flatheaded borer
peach tree borer
peach twig borer
pear blight beetle
pear psylla
pear leaf-curling midge
pear sawfly
pine needle scale
pine and cone spittlebug
poplar and willow borer
Psyllopsis fraxinicola
rose curculio weevil
rose midge
rove beetle gallery
rose stem girdler
sequoia pitch moth
soldier beetle gallery
snapdragon plume moth new
snakefly gallery
speckled green fruitworm
meadow spittlebug
spotted asparagus beetle
spruce twig aphid
tent caterpillars
viburnum leaf beetle
violet gall midge
western poplar clearwing
western spotted cucumber beetle
white pine weevil
woolly alder aphid new
woolly ash aphid
woolly beech aphid

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Pacific flatheaded borer

Damage from the Pacific flatheaded borer, Chrysobothris mali, often can be seen in late August and September in shade tree production. The following images were taken during August of flatheaded borer damage and larvae on cherry and plum trees. Adult borers emerge from late May-June and are reported to fly for about one month.

Insecticides are not always recommended for this pest in field nursery production. Rather many growers in field-grown production rogue out and burn thoroughly infested material. Container shade tree producers are more apt to make protective applications, given the higher investment costs associated with those trees.

Monitoring for Pacific flatheaded borers is generally done with colored traps for these visually-oriented beetles (as opposed to the use of pheromone or ethanol traps). Purple-colored sticky traps have been used for Buprestid beetles such as flatheaded borers and emerald ash beetle. The use of traps help to determine the flight of the adult beetles. Awareness of the flight, may help with timing of protective applications and scouting for injured trees and localized pockets of damage.

If possible, determine if there have been causes of stress to the trees. Drought stress, sunburn, flooding, and tree wounds are some of the underlying factors making trees susceptible to flatheaded borer damage. Trees adjacent to natural wooded areas with weakened trees that might host the beetles, may also be more susceptible.


Oregon State University Pacific flatheaded borer fact sheet

Forest Pests of North America: Pacific flatheaded borer

Original version: <2 September 2003)

Last update <29 December 2016>

Author: R.L. Rosetta, Extension Nursery Integrated Pest Management, Department of Horticulture, Oregon State University/NWREC.

Sawdust or frass from wound on cherry
borer frass
Frass and weeping on plum
borer frass on plum
More subtle frass evidence on plum
frass on plum
Weeping wound on cherry
weeping damage

Multiple Pacific flatheaded borer larvae in cherry
Multiple Pacific flatheaded borer larvae in cherry

Closeup of Pacific flatheaded borer larvae and galleries in cherry
Pacific flatheaded borer larvae and galleries in cherry
Pacific flatheaded borer larva
flatheaded borer larva
Pacific flatheaded borer adult
Pacific flatheaded borer adult
Photo: Ken Gray

Pacific flatheaded borer larva

Website editor:
Robin Rosetta

Page last modified 12/29/16


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