Insect Pests on Trees & Shrubs

• Aphid
• Apple Maggot 
  
• Ash Bark Beetle 
  
• Ash Leaf Cone Caterpillar 
  
• Ash Plant Bug 
  
• Birchleaf Miner 
  
• Cottony Psyllid 
  
• Dogwood Sawfly 

• Elm Leaf Miner
• Elm Scale
• Europhid Mite
• Leaf Cutter Bees
• Leaf Hopper
• Leaf Rollers on Aspen
• Microscopic Mites
• Oak Gall
  

• Oak Mite
• Pear Slug
• Poplar Willow Borer
• Scurfy Scale
• Spider Mites
• Thrips
• White Pine Weevil
• Wooly Bears
  

     For all chemical controls, READ AND FOLLOW LABEL INSTRUCTIONS THOROUGHLY BEFORE USE

APHID

Plants Affected

• Numerous

Symptoms

• Severe infestations will cause curling/twisting of foliage, flowers to wilt and drop.

Controls

Cultural or Non-chemical Controls:

• Ladybird beetles/larvae, lacewings are natural predators.
• Strong jet of water to knock aphids off plants.

Chemical Controls:

• Insecticidal soap, Doktor Doom House and Garden, and various other insecticides.

APPLE MAGGOT

Plants Affected

• Apple, Evans Cherry, Hawthorn.
• Worse on early ripening apples.

Symptoms

Life Cycle

• Adults lay eggs in fruit early to mid July. Maggots make trails rendering fruit inedible (outside pockmarked).
• Larvae drop to ground and pupate until the next June – July.

Controls

Cultural or Non-chemical Controls:

• Lay a barrier (landscape fabric, remay cloth) on top of soil under the tree—this prevents pupae from emerging from soil, as well as larvae entering soil in fall.

• Apple Maggot Traps—hang in trees in mid-late May.  Average emergence date in Alberta is June 15-23.

Chemical Controls:

• None

ASH BARK BEETLE

Plants Affected

• Ash

Symptoms

• Wilting, yellowish foliage.
• Check under bark for adults/galleries.

Controls

Cultural or Non-chemical Controls:

• Keep garden debris free (ants are feeding on debris).
• Pour boiling water down hills.
• Keep area well watered-ants don't prefer wet areas.
• Control aphid colonies.

Chemical Controls:

• Pyrethrum
• Diatomaceous earth
• Doktor Doom Residual-yellow can

ASH LEAF CONE
CATERPILLAR

Plants Affected

• Ash

Symptoms

• Leaves rolled into cones - damage cosmetic.

Controls

Cultural or Non-chemical Controls:

• Parasitic wasp is helping control.
• Handpick small infestations.
• Good leaf cleanup in fall.

Chemical Controls:

• None – spraying will kill beneficial insects that provide control.

ASH PLANT BUG

Plants Affected

• Green Ash

Symptoms

• Leaves turn yellow, are mottled. May see stippling - (like a mite).
• Drought /stress related.
• Damage is cosmetic.

Controls

Cultural or Non-chemical Controls:

• Keep trees stress free, especially in droughts.
• Prune any dead/dying branches.

Chemical Controls:

• Apply Tanglefoot in spring to block adults travel.

BIRCH LEAF MINER

Plants Affected

• Birch

Symptoms

• Watch for mines in leaves, yellowing leaves.

Controls

Cultural or Non-chemical Controls:

• Has been kept under control very well by beneficial insects.
• Keep trees well watered.

Chemical Controls:

• Not necessary.

COTTONY PSYLLID

Plants Affected

• Ash, Elder
• Plants stressed by drought are most susceptible.

Symptoms

• Twisted, distorted foliage—eventually browns and drops.

Controls

Cultural or Non-chemical Controls:

• Prune out severely affected portions to encourage new growth from below.
• Horticultural oil spray can be applied to buds in spring BEFORE buds open.
• Keep trees well watered during dry spells.

Chemical Controls:

• Safer's Soap

DOGWOOD SAWFLY

Plants Affected

• Dogwood

Symptoms

• Foliage has holes in it.
• Larvae have white or cream coloring with black dots on body.
• Larvae turn darker with larger spots as they mature.

Controls

Cultural or Non-chemical Controls:

• Handpick small amounts

Chemical Controls:

• Spray with Sevin, Malathion, or Ambush (BTK will not work because these are not larvae of moths and butterflies but larvae of sawflies).

ELM LEAF MINER

Plants Affected

• Elm

Symptoms

• Leaves are "mined".

Controls

Cultural or Non-chemical Controls:

• With small infestations, handpicking mined leaves is effective.

Chemical Controls:

• Insecticidal soap or sevin applied in late May/June as soon as mines are first noticed.

ELM SCALE

Plants Affected

• Elm

Symptoms

• Honey Dew, sooty mold.
• Branches die back.

Controls

Cultural or Non-chemical Controls:

• With small infestations, run gloved hand along bark to dislodge scales.

Chemical Controls:

• Horticultural Oil in early spring.

EUROPHID MITE ON CRANBERRY

Plants Affected

• Cranberry

Symptoms

• Small gall like growths are seen on the surface of maple leaves in early to mid summer.

Controls

Cultural or Non-chemical Controls:

• Prune out affected sections as soon as damage noted.
• Spray with Horticultural oil either infFall after leaves are shed or in spring before bud break.

Chemical Controls:

• No chemical insecticides are effective; damage is cosmetic and will not harm tree.

EUROPHID MITE ON MAPLE

Plants Affected

• Maple

Symptoms

• Portions of new leaves are covered in fuzzy like material; commonly mistaken for a fungal disease.

Controls

Cultural or Non-chemical Controls:

• Prune out affected sections as soon as damage noted.
• Spray with Horticultural oil either in fall after leaves are shed or in spring before bud break.

Chemical Controls:

• No chemical insecticides are effective; damage is cosmetic and will not harm tree.

LEAF CUTTER BEES

Plants Affected

• Rose, Lilac, Ash, Virginia Creeper

Symptoms

• Half moon shapes cut out of leaves.
• Use leaves to seal eggs into the cells of the hive.
• May pollinate garden crops - do pollinate alfalfa
• Cosmetic

Controls

Cultural or Non-chemical Controls:

• Keep dead stems pruned back to live tissue.

Chemical Controls:

• Not necessary.

LEAF HOPPER
- NOT WHITEFLY

Plants Affected

• Many—seen lots on Ash, Linden, Virginia Creeper.

Symptoms

• Sap suckers—deform leaves by stippling them.
• Insects jump away when you near the plant.

Controls

Cultural or Non-chemical Controls:

• Strong jet of water will knock them off plants
• Ladybugs, birds feed on them.

Chemical Controls:

• Insecticidal Soap
• Permethrin (note: Doktor Doom more effective)

LEAF ROLLERS
ON ASPEN

Plants Affected

• Aspen

Symptoms

• Rolled leaves, defoliation.  Considered cosmetic.

Controls

Cultural or Non-chemical Controls:

• Parasitic wasps help control.
• Tanglefoot at base of tree may prevent pupae from crawling up tree.

Chemical Controls:

• Horticultural Oil in early spring may smother eggs.

MICROSCOPIC MITES

Plants Affected

• Various plants—see symptoms

Symptoms

• Alder and Maple - red bumps
• Plum - ‘fingers’
• Elder - looks like herbicide damage/cottony psyllid damage (can look like spaghetti).
• Viburnum- looks like mildew initially. Red colouration follows.
  

Controls

OAK GALL

Plants Affected

• Oak

Symptoms

• Various growths caused by mites, wasps or aphids.

Controls

Cultural or Non-chemical Controls:

• Good fall cleanup.

Chemical Controls:

• Various galls at play – some overwinter on tree, some not. Spray Horticultural Oil in spring as a preventative.

OAK MITE

Plants Affected

• Oak

Symptoms

• Small round shaped multi coloured galls appear like 'Fruit Loops' on back side of Oak leaves.

Controls

Cultural or Non-chemical Controls:

• Prune out affected portions when first noted.
• Damage is cosmetic as galls will not kill tree.

Chemical Controls:

• No chemical controls of note.

PEAR SLUG

Plants Affected

• Fruit trees, Cotoneaster, Mountain Ash, Hawthorn

Symptoms

• Leaf skeletonizing in mid to late June and again late July/August

Controls

Cultural or Non-chemical Controls:

• Pick off larvae, hose off with strong jet of water.
• Bark mulch may deter adults emergence.

Chemical Controls:

• Not recommended-birds, parasitic wasps control these. If you choose to spray, use Safer's 3 in 1 Garden Spray.

Poplar Borer
(Poplar Willow Borer)

Plants Affected

• Aspen and Willows

Symptoms

• Holes in Aspen or Willows, and sawdust near the base of the plants.

Controls

Cultural or Non-chemical Controls:

• Ambush or Doktor Doom Home & Garden (both contain the active ingredient of Permethrin).

Chemical Controls:

• Wilson's Borer and Weevil Killer

SCURFY SCALE

Plants Affected

• Ash, Aspen, Cotoneaster, Dogwood, Willow
• Attacks mainly Cotoneaster, Rose Family.
  

Symptoms

• Scales cluster together.
• Mistaken for fireblight, kills twigs/branches.

Controls

Cultural or Non-chemical Controls:

• Prune damaged branches (disinfect between cuts).
• Natural predators include lacewings and ladybird beetles.
• Horticultural oil or Lime Sulphur can be applied in spring to suffocate eggs;apply half strength on Cotoneaster as they do not have a protective bud cover.

Chemical Controls:

• Malathion, Permethrin end of June.

SPIDERMITES

Plants Affected

• Numerous

Symptoms

• Stippling—tiny dots in foliage.
• Yellowing of foliage—’haze’ on foliage
  

Controls

Cultural or Non-chemical Controls:

• Strong jet of water
• Keep plants misted
• Fall debris cleanup

Chemical Controls:

• Insecticidal Soap, miticide such as malathion, Safer's 3 in 1. Product must state:Miticide or that it treats Mites.

THRIPS

Plants Affected

• Numerous

Symptoms

• White blotches or streaks on foliage/blooms

Controls

Cultural or Non-chemical Controls:

• Good fall clean up of debris.

Chemical Controls:

• Apply Doktor Doom to foliage early in season (mid-June). As this product persists on foliage for a few weeks, it should help to get one the generations.
• Doktor Doom House and Garden

WHITE PINE WEEVIL

Plants Affected

• White Pine

Symptoms

• Symptoms appear on most types of pine and sometimes spruce.
• Terminal leader of pine and spruce become curled over resembling a shepherds hook.
• Small exit and entry holes are seen at the base of the leader.

Controls

Cultural or Non-chemical Controls:

• Remove leader.
• Trees must be kept healthy (well watered).
  

Chemical Controls:

• No regulated chemicals.

WOOLY BEARS -
Tussock Moth Larva

Plants Affected

• Several

Symptoms

• Damage is cosmetic.

Controls