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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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). Leaves can be so heavily mined that the trees defoliate. Most trees flush again and do fine. Camperdown elms often hold onto partially mined leaves which can be an aesthetic problem (Sharon Collman, pers. comm.).

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).

Monitor for adults when sun is present on the foliage in order to better see them. First tiny mines are also a good indicator. 


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 4/20/16


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