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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Pear blight borer

The pear blight beetle (also known as European shot-hole borer), Anisandrus (= Xyleborus) dispar, lives up to one of its names leaving trees with small diameter holes resembling tiny shot holes. An investigation of borer activity in Oregon nurseries indicated that this species of ambrosia beetle is active in various sites in the Willamette Valley. We've identified this borer in damage from container and field production sites. Click the hyperlink below to see a very informative website regarding this beetle.

The Shothole Borer: An Ambrosia Beetle of Concern for Chestnut Orcharding in the Pacific Northwest

Identification aid is available at the Anisandrus link at the Bark Beetles of the United States website.

The beetle has a large host range. Hosts include: Acer, Aesculus, Alnus, Betula, Castanea, Celtis, Crataegus, Corylus, Cydonia, Fagus, Fraxinus, Juglans, Liriodendron, Magnolia, Malus, Platanus, Populus, Prunus, Punica, Pyrus, Quercus, Salix, Styrax,Tilia, Ulmus, and Vitis (Additional hosts can be found in the Plantwise Pear Blight Beetle webpage). There are also reports from Pinus, Cedrus, and Tsuga.

The European shot hole borer overwinters as adults. It is not uncommon to find the rear end of the beetle protruding from the hole it bore. After wintering inside a suitable host, the female X. dispar beetle takes advantage of the first warm day in late winter or spring to seek another host, preferably a tree exhibiting signs of stress. The much smaller male is flightless, staying in the tree in which it was born. The female’s initial attraction is to ethanol emitted by stressed trees. Once the female shothole borer finds a good host, she sends out an aggregation pheromone which attracts beetles of the same species. This volatile chemical is responsible for secondary attacks on trees, with hordes of beetles gathering on that tree or others nearby. Thus shothole borers often leave trees riddled with entrance holes. It is thought that X. dispar has two flights per year in Oregon, in early spring (our trap catches show a peak in late March/early April) with activity into May and June.

Check for current damage in trees which might have experienced stress. Sap weeping from the small diameter wounds is one symptom readily seen. Fresh sawdust on the trunk indicates recent entry or emergence of the adults. These beetles often appear in large numbers even on the same tree.

Beetle flights occur when temperatures reach 50 degrees F, particularly on a bright, sunny day. We have found it extremely helpful for growers with a history of shothole borers to monitor flights of the borers. The Lindgren funnel trap with an ethanol lure (Contech) was used successfully in our research to obtain flight data for several common borers. Reding and colleagues have found using two ethanol lures increased the trap catch of two shothole borers, X. crassiusculus and X. germanus. We do not know if this would be the case with shothole borers more commonly found in Western Oregon.

Improve growing conditions to reduce stressed trees. Drought, waterlogged soils, and freeze damage can all lead to increased risk of borer damage. In container nurseries, keeping the plant media of flood-intolerant trees below 50% moisture levels greatly reduces or eliminates ambrosia beetle attacks (Ranger et al. 2016). In field nurseries, susceptible trees may be rogued and burned or treated with long residual protective insecticide applications during beetle flight periods to reduce risk of damage [See PNW Insect Management Handbook recommendations].

(Disclaimer: listing or not listing of specific resources is not an endorsement or lack of endorsement).

Ethanol lures

AgBio Inc.

Alpha Scents

Forestry Distributing

Horizon Biosciences

Literature cited:

Ranger, C., P. Shultz, M. Redding, S. Frank, and D. Palmquist. 2016. Flood Stress as a Technique to Assess Preventative Insecticide and Fungicide Treatments for Protecting Trees Against Ambrosia Beetles. Journal of IPM. 2016. 7(40). 11 p. (February 2017)

Reding, M., Shultz, P.B., Ranger, C.M., and J.B. Oliver. 2011. Optimizing ethanol-baited traps for monitoring damaging ambrosia beetles (Coleoptera: Curculionidae, Scolytinae) in ornamental nurseries. J. Econ. Entomol. 104(6):2017-24. <8 June 2017>

Schuh, J. and D.C. Mote. 1948. Insect Pests of Nursery and Ornamental Trees and Shrubs in Oregon.

H. Omroa Bhagwandin, Jr. The Shothole Borer: An Ambrosia Beetle of Concern for Chestnut Orcharding in the Pacific Northwest. Western Chestnut Growers Assn.

Original: 7 May 2011

Updated 8 June 2017.

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

A. dispar adult beetle (female)
A. dispar adult beetle (female)
Female (lower left) and male (upper right) A. dispar beetles
Female (lower left) and male (upper right) A. dispar beetles
First instar larva, pupa, male and female imago
Larva, pupa, male and female A. dispar beetles
A. dispar adult, larvae, and eggs in gallery
A. dispar adult and eggs in gallery
Close up shot of A. dispar adult, larvae, and eggs in gallery
Anisandrus dispar adult, larvae, and eggs in gallery
Beech (Fagus) infested with European shot hole borer
Beech infested with shot hole borer
A. dispar near entrance holeAdult Anisandrus near hole
Holes from A. dispar emergence
image of borer damage
Photo: Rosetta
Weeping wound on plumweeping wound
Photo: Anonymous
Weeping wound on container plum
weeping wound from borer
Photo: Eric Smith
Lindgren funnel trap
Lindgren funnel trap
Photo: Eryn Cramer
Website editor:
Robin Rosetta

Page last modified 2/23/17


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