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
azalea sawfly New
bark lice
Barypeithes root weevil Updated
Beneficial nematodes
biocontrol of root weevils
birch aphid Updated
black bean aphid New
black stem borer
bluegum psyllid
borers
branch and twig borer
brown marmorated stink bug

bronze birch borer
boxwood leafminer
boxwood psyllid Updated
bulb flies
cabbage whitefly new
carpet beetle (images)
Calligraph californica
caterpillars

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

dogwood sawfly
Douglas fir sawfly
Douglas fir twig weevil
dustywings New
earwigs
elm leafminer
European pine shoot moth
European wool carder bee
emerald ash borer
Fall webworm
flatheaded cedar borer
ground beetle gallery New
hollyhock weevil
honeylocust plant bug
honeylocust pod gall midge
Heliothis phloxiphaga
holly bud moth
huckleberry root aphids
ground mealybug
lacebugs
lacewings New
lady beetle gallery Updated
leaf weevil
light brown apple moth
maple aphids Updated
maple tip moth
maple midge
March flies Updated
mountain ash sawfly
Narcissus bulb fly Updated
Natural enemies gallery new
spruce twig aphid
oak ambrosia beetle
oak slug
oak twig gall wasp new
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
roseslug
rove beetle gallery New
sawflies
scale
sequoia pitch moth
soldier beetle gallery New
snakefly gallery New
speckled green fruitworm
meadow spittlebug updated
tent caterpillars
thrips
viburnum leaf beetle
violet gall midge
western poplar clearwing
western spotted cucumber beetle
white pine weevil Updated
whiteflies
woolly ash aphid
woolly beech aphid Updated

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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. 

Literature:

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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