Contents: By Damage and Image
(In progress)
Contents: Alphabetical
alder flea beetle
aphid management
apple and thorn skeletonizer
apple ermine moth
ash whitefly new
azalea bark scale
azalea lace bug
bark lice
Barypeithes root weevil Updated
Beneficial nematodes
biocontrol of root weevils
birch aphid Updated
black stem borer
bluegum psyllid
branch and twig borer
brown marmorated stink bug

bronze birch borer
boxwood leafminer
boxwood psyllid Updated
bulb flies
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
cypress tip moth

dogwood sawfly
Douglas fir sawfly
Douglas fir twig weevil
elm leafminer
European pine shoot moth
European wool carder bee
emerald ash borer
Fall webworm
flatheaded cedar borer
hollyhock weevil
honeylocust plant bug
honeylocust pod gall midge
Heliothis phloxiphaga
holly bud moth
huckleberry root aphids
ground mealybug
lady beetle gallery
leaf weevil
light brown apple moth
maple aphids Updated
maple tip moth
maple midge
March flies Updated
mountain ash sawfly
Narcissus bulb fly Updated
spruce aphid on spruce
oak ambrosia beetle
oak slug
obscure root weevil
Pacific flatheaded borer
peach tree borer
peach twig borer
pear blight beetle Updated
pear psylla
pear leaf-curling midge
pear sawfly
pine needle scale
pine and cone spittlebug New
poplar and willow borer
rose curculio weevil
rose midge
sequoia pitch moth
speckled green fruitworm
meadow spittlebug updated
tent caterpillars
viburnum leaf beetle
violet gall midge
western poplar clearwing
western spotted cucumber beetle
white pine weevil Updated
woolly ash aphid
woolly beech aphid Updated

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European shot-hole borer

The European shot-hole borer (also known as pear blight beetle), Anisandrus (= Xyleborus) dispar, lives up to its name 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.

Improve growing conditions to reduce stressed trees. Drought, waterlogged soils, and freeze damage can all lead to increased risk of borer damage. In nurseries, susceptible trees may be treated with long residual protective insecticide applications during beetle flight periods to reduce risk of damage [See PNW Insect Management Handbook recommendations].

Literature cited:
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.

Revised 29 February 2016.

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 hole
X. dispar adult
Photo: Rosetta
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 2/29/16


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