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

bronze birch borer
boxwood leafminer
boxwood psyllid
bulb flies
carpet beetle New
Calligraph californica
caterpillars

Ceanothus stem gall moth
cereal leaf beetle
cherry ermine moth
chilli thrips
clay colored weevil
cottony camellia scale
cutworm Updated
craneflies
cypress tip moth

dogwood sawfly
Douglas fir sawfly
Douglas fir twig weevil
earwigs
elm leafminer
European pine shoot moth
European shot-hole borer
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
lacebugs
lady beetle gallery
leaf weevil
light brown apple moth
maple tip moth
maple midge
March flies
mountain ash sawfly
spruce aphid on spruce
oak ambrosia beetle
oak slug
obscure root weevil
Pacific flatheaded borer
peach tree borer
peach twig borer
pear psylla
pear leaf-curling midge
pear sawfly New
pine needle scale
poplar and willow borer
rose curculio weevil
rose midge
roseslug
sawflies
scale
sequoia pitch moth
speckled green fruitworm
spittlebug
tent caterpillars
thrips
viburnum leaf beetle
violet gall midge
western poplar clearwing
western spotted cucumber beetle
white pine weevil
whiteflies
woolly ash aphid

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White pine weevil

The white pine weevil, Pissodes strobi, is a key pest in conifer production. This is primarily due to its feeding damage to the terminal of conifers causing flagging and dieback. It most commonly attacks spruce in nursery production in the PNW.

Description
White pine weevil larvae are white, c-shaped grubs with a brown head capsule. White pine weevil adults are black with reddish-brown and white spots on the elytra and a long black snout from which their bent antennae arise. They have fully-functioning wings.

Damage
Adults feed on the terminals, chewing through the bark. Small punctures and sap on the terminals are evidence their feeding damage. They oviposit (deposit eggs) into these feeding wounds . The larvae hatch from these eggs, feeding in the cambial tissue under the bark, causing characteristic wilting, and eventual death of the terminal.

The weevil larvae pupate in pupal chambers lined with sawdust under the bark and emerge as adults in mid-late summer. The adults feed in the trees until they return to the duff at the base of the tree to overwinter. There is one generation a year.

Monitoring
In the early spring, monitor for adult weevils that have emerged from the duff at the base of trees. Michigan State University Extension recommends the use of Tedder traps to trap the adult weevils as they emerge. They mention they begin trapping adult weevils at 35 GDD50 (35 accummulated Degree Days at using a base of 50 degrees Fahrenheit). Research in Pennsylvania showed emergence once soil temperatures in the top two inches were 50 degrees Fahrenheit or 10C. Ohio State's Phenological Indicator site has adult emergence at 84 degree days and nearby phenological indicators are first bloom of star magnolia and first bloom of border forsythia.

Cultural Management
Cut out damaged terminals and remove these prunings from the nursery.

Chemical Management
Chemical management is timed to prevent successful oviposition by the winged adult weevils that feed and oviposit in the spring. An insecticide application is applied to the terminals of the trees.

For chemical recommendations, check the nursery section at the PNW Insect Management Handbook.

Additional Web Resources

White pine weevil. USDA Forest Service Forest Insect & Disease Leaflet 21. A very thorough presentation on the biology, ecology, and management of white pine weevil with good images. The emphasis is silviculture but much pertains to nurseries.

The White Pine Weevil Homepage. Natural Resources Canada

White Pine Weevil Fact Sheet. Penn State Woody Ornamental Integrated Pest Management

Gardosik, S. and R. Leyman. 2005. White Pine Weevil Detection Traps. PA Department of Agriculture. Instructions on how to use Tedder traps for detection of white pine weevil adult emergence.
Accessed 31 March 2012.

White Pine Weevil from OSU Extension

White pine weevil oviposition holes
white pine weevil oviposition holes
White pine weevil egg
white pine weevil egg

Early signs of white pine weevil damage
white pine weevil damage
Wilting and crooknecking of shoots due to white pine weevil
white pine weevil damage
Further wilting and crookneck symptoms on blue spruce
white pine weevil damage
Early and late symptoms of damage on blue spruce due to white pine weevil
white pine weevil
Late symptoms of white pine weevil damage
late symptoms of white pine weevil damage
The easily peeled-back bark reveals numerous larvae
white pine weevil larvae
White pine weevil larvae under the loose bark
white pine larvae
White pine weevil larva
white pine weevil larva
White pine weevil pupal chambers
white pine weevil pupal chambers
White pine weevil larva in pupal chamber
white pine weevil in pupal chamber
White pine weevil larvae in pupal chambers
white pine weevil in pupal chambers
White pine weevil adults
white pine weevil adults


 
Website editor:
Robin Rosetta

Page last modified 3/31/14

 

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