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Contents: Alphabetical
alder flea beetle
aphid management
apple and thorn skeletonizer
apple ermine moth
ash whitefly new
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
branch and twig borer
brown marmorated stink bug

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

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

dogwood sawfly
Douglas fir sawfly
Douglas fir twig weevil
elm leafminer
European pine shoot moth
European shot-hole borer Updated
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 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
sequoia pitch moth
speckled green fruitworm
tent caterpillars
viburnum leaf beetle
violet gall midge
western poplar clearwing
western spotted cucumber beetle
white pine weevil
woolly ash aphid

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Elm leafminer

The elm leafminer, Fenusa ulmi, has been in the Northwest for a few years but has been noticeable in its expansion to new areas in Washington and Oregon recently. The sawfly attacks Scotch and Camperdown elms, Ulmus glabra), Engish elm, U. procera; and American elm (Johnson and Lyon, 1991). Scannell reported no damage on American elm in her research (Scannell, 2000).

According to research by Christine Scannell at the the University of Washington, the adult sawflies emerge coinciding with the breaking of the leaf buds of most elms, although after leaf expansion of American and European white elms (Scannell, 2000). The timing of emergence ranged from mid-March through mid-April depending on temperatures during the course of several years of study.

The sawflies tend to emerge during the middle of the day with maximum emergence occurring between11:00 am and 1 pm. The adults are all female and begin to lay eggs immediately after emergence. The eggs are usually laid near leaf veins initially but later oviposition is without regard to location of the veins (Scannell, 2000).

There are five instars of the larvae. In 2000, the larvae were found 10 days after the first emergence of the adult sawflies (Scannell, 2000). The larvae eventually drop to the ground where they are reported to pupate through the summer, fall, and winter. There is one generation per year (Johnson and Lyon, 1991).



Johnson, W.T. and H.H. Lyon. 1991. Insects that Feed on Trees and Shrubs. 2nd. Ed. Cornell University Press. 560 pp.

Scannell, C.M. 2000. The Biology and Seasonal Life History of the Elm Leaf Miner, Fenusa ulmi (Sundevall), in the Pacific Northwest (Hymenoptera: Tenthredinidae). Master's Thesis, University of Washington.



Elm leafminer damage
elm leafminer damage
Photo: Eric LaGasa, WSDA
Elm leafminer damage
elm leafminer damage
Photo: Eric LaGasa, WSDA
Elm leafminer silhouettes. Note that the leaf is completely mined.
elm leafminer silhouettes
Photo: Rosetta
Elm leafminer larva removed from mine.
elm leafminer larva

Photo: Rosetta
Website editor:
Robin Rosetta

Page last modified 6/15/04


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