Contents: By Damage and Image
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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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Pear sawfly

Pear sawfly, , Caliroa cerasi (L.), is also known as pear slug, cherry slug, and cherry sawfly, and is just one of many sawflies that may feed on ornamental plants.

While pear slugs look similar to small slimey slugs, they are actually larvae of little, dark, thick-waisted wasps which are about 1/5 inch (5 mm) long. The larvae range in size from 0.06 inch to 3/8 inch (1.4-10 mm) long. They are covered in an olive green-to-black layer of slime. They have three pairs of true legs that are barely noticeable under their body.

Life cycle
The overwintering stage is spent as a pupa in a cocoon located about two-to-three inches below the the soil. The adult wasps emerge from the soil in the late spring (April or May) and fly to host plants nearby. Eggs are inserted into leaf tissue. The larvae hatch and go through five stages. They feed for about two-to-three weeks. They then drop to the ground and pupate after the last stage. There are two generations per year. The first brood of larvae is most abundant during June and July. The larvae of the second generation occurs in August and September.

Host plants of pear sawfly includes apricot, cherry, cotoneaster, hawthorn, mountain ash, pear, prune, and quince.

The feeding damage on the leaf first looks like scattered brown spots. As the larvae feed the damage resembles tiny, expanding windowpanes in the leaf. Over the season, the entire leaf may be hollowed out, leaving only the plant veins. Heavily damaged leaves may drop from the plant. The lower leaves are commonly affected first and gradually leaves farther up the trunk are infested. Athough there is some tolerance for damage on the lower leaves, shade tree terminals can be damaged by high populations and continuous feeding by pear sawfly can weaken or stunt nursery stock.


Strong jets of water can be used to dislodge limited numbers of pear slugs. Similarly, hand picking of sawflies or infested leaf removal may be useful with small, isolated populations or small plants.

Sawflies are susceptible to a range of pesticides. Research from Colorado State evaluated abamectin (Avid 0.15 EC) + superior oil (Sunspray UltraFine Oil), spinosad (Conserve SC), permethrin (Astro), and thiomethoxam (293,343 25 G) for management of pear sawfly on cotoneaster. All treatments provided effective control. See the Guidelines from the PNW Insect Management Handbook for Nurseries or Landscapes under sawflies.

Web Resources

Antonelli, Art. Insect Answers: Pear Slug. Washington State University Extension Fact Sheet. 3 June 2104.

Berry, R. Pear sawfly.Insects and Mites of Economic Importance in the Pacific Northwest. Oregon State University Fact sheet on pearslug. 3 June 2104.

Cranshaw, W.S. and D.A. Leatherman. 2004. Pear slugs. Colorado State University Extension. Updated January 08, 2014. 2 June 2014.

Long, Lynn. 1993. Pear sawfly (pear slug). Orchard Pest Management Online. Tree Fruit Research and Extension Center. Washington State University. 2 June 2014.

Sharon J. Collman and Michael R. Bush. 2013. Pear, flowering (Pyrus)-Pear sawfly (pear slug). PNW Insect Management Handbook. 2 June 2014.

Varela, et al. UC Pest Management Guidelines: Pearslug. 3 June 2014. Note: recommendations are for commercial fruiting pear production.


Additional References:
Berry, Ralph. 1998. Insects and Mites of Economic Importance in the Pacific Northwest, 2nd Ed. OSU Bookstore, Inc. Corvallis, OR, USA. 221 pp.

Schuh, J. and D.C. Mote. 1948. Insect Pests of Nursery and Ornamental Trees and Shrubs in Oregon. Station Bulletin 449. Agricultural Experiment Station, Oregon State College, Corvallis, OR, USA. 164 pp.

Pear sawfly damage on upper leaf surface of 'Mazzard' cherry
pear sawfly damage
Pear sawfly and feeding damage on underside of leaf from 'Mazzard' cherry
pear sawfly larva and damage

Close up of pear sawfly larva and damage
closeup of pear sawfly and damage

Close up of pear sawfly larva and damage
pear sawfly larva
Photo: Ken Gray
Pear sawfly pupa in cocoon
pear sawfly pupa in cocoon
Photo: Ken Gray
pear sawfly adult
adult pearslug
Photo: Ken Gray

Pear sawfly on' Mazzard' cherry leaf
pear sawfly (tentative ID)  on 'Mazzard' cherry leaf
pear sawfly eggspearslug eggs
Photo: Ken Gray
pear sawfly larva and damagepearslug larva and damage
Photo: Ken Gray
Website editor:
Robin Rosetta

Page last modified 6/3/14


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