Brochures

Plant Problems

Garden Insects

The following is basic information about identifying the pests that attack various plants in your yard and garden.

Vegetable Pests

Aphids
pear-shaped, soft bodied insects often found in colonies.  Can be pale green, yellow, brown, black or pink. 
  • Injure plant by sucking sap causing leaf distortion and reduced growth; can   transmit diseases
  • Attack - all vegetables
Colorado Potato Beetle
rounded, hard shelled beetles, alternating black and yellow stripes; larvae are red humpback with two rows of black spots on each side
  • Feed heavily on leaves and stems, small plants are most severely damaged
  • Attack - eggplants, peppers, potatoes and tomatoes
Flea Beetles
small black or black and yellow beetles that jump like fleas eat pin-sized holes in the leaves destroying the leaves
  • Attack - cabbage, beets, broccoli, Brussels sprouts, corn, eggplant, kohlrabi, potato, radish, rutabaga, tomato, turnip
Root Maggots
small, white, legless maggots
  • Maggots tunnel into roots rendering them inedible.  Plant appear stressed, leaves may turn yellow.  In severe cases plants may wilt and die
  • Attack - broccoli, Brussels sprouts, cabbage, cauliflower, radish, rutabaga, turnip and others
Cutworms
fleshy, caterpillar-like worms that curl up when disturbed.
  • Sever stems at or just below ground level.  Feed at night
  • Attack - all vegetables
European Corn Borer
large green, brown or pink caterpillars with dark brown head found inside the stalks or within the ears
  • Feeds on leaves, stalks and ears.  Leaves are riddled with tiny shot holes; bores into stalks or ears to feed on the cob and kernels
  • Attack - corn and tomatoes
Cabbageworm
velvety green caterpillar with a yellow stripe running down its back
  • Chew ragged holes in the leaves; may bore into heads and contaminate edible portions
  • Attack - broccoli, Brussels sprouts, cabbage, cauliflower, kale, radish, turnip 
Leafhoppers
small pale green insects that jump and fly
  • Damage plants by sucking the sap. Leaves may be stippled, curled, puckered or brittle.  Carry and transmit viruses and  diseases
  • Attack - carrots, celery, cucumber,  lettuce, potato
Thrips
tiny, slender, pale yellow, green or brown insects
  • Feed by rasping plant tissue then sucking the released plant sap.  The injured tissue dies, producing dead spots, distorted blooms and leaves and balled flowers.  
  • Attack - bean, cabbage, onion, pea and other crops

Evergreen Pests

Aphids
pear-shaped, soft bodies insects
  • Suck sap while feeding on the branches and needles; causes a reduction in plant vigour; excrete sticky honeydew on which sooty / black molds grow
  • Attack - all evergreens
Pine Needle Scale
tiny white, flattened scaly insects
  • Suck sap from needles causing needles to develop a yellow mottling, turn brown then drop
  • Attack - spruce, pine, fir, hemlock and cedar
Sawflies
small light green caterpillars with a black head or yellowish caterpillars with yellow-orange head
  • Feed on needles - defoliating branches; causes stress which can make plants vulnerable to other pests and diseases
  • Attack - spruce, larch, cedar, pine
Spruce Budworm
yellow caterpillar with a dark brown head are covered with white spots
  • Feed on developing buds and needles; in severe cases all new growth will be consumed
  • Attack - Spruce, fir
Spruce Gall Aphid
pear-shaped, white, wooly soft-bodied insects
  • Cause the formation of galls at the tips of the branches - feed on new growth.  Galls emerge green, turn purple then eventually brown.  Galls cause tip kill and may distort or yellow needles
  • Attack - Spruce, fir
Spider Mites
tiny, rounded, eight-legged insects
  • Puncture foliage and suck plant sap; foliage becomes stippled yellow and looks dirty.  A fine webbing may be present
  • Attacks - all evergreens
White Pine Weevil
white, legless larvae with light brown heads; adult is a dark brown beetle with a prominent snout
  • Feed under the bark of new leaders eventually girdling the stem.  The leader wilts - looks like a shepherds crook
  • Attacks - spruce, pine

Tree, Shrub, Rose, Perennial and Annual Pests

Aphids
pear-shaped, soft bodies insects
  • Suck sap while feeding on leaves; causes a reduction in plant vigour, wilting and distortion of leaves and flowers; excrete sticky honeydew on which sooty / black molds grow.  In some cases can cause red blistering on leaves.
  • Attack - all herbaceous and woody ornamentals

Blister Beetles
long, slender, black, purple or metallic green beetles
  • Chew rounded holes into leaves
  • Attack - annuals and perennials

Blister Mites
tiny white mites
  • Cause reddish, yellow or brown blisters on the leaves
  • Attack - Mountain Ash, cotoneaster, pears, apples

Box Elder Bugs
brownish-black insects with red stripes on the wings
  • Suck nutrients from the seeds, foliage and young stems.  Damage to trees is minor
  • Attack - Manitoba Maple

Caterpillars
common types loopers, cankerworms, larvae for moths and butterflies
  • Chew irregular holes in foliage; severe cases may cause defoliation.  Only in severe cases will the overall tree health be affected
  • Attack - all ornamentals

Flee Beetles
very small, shiny black beetles that hop
  • Chew holes or skeletonize leaves
  • Attack - poplar, willow and other woody ornamentals

Forest Tent Caterpillar
large blue-black caterpillars are marked with white spots along the back
  • Chew large, irregular holes in foliage causing defoliation of entire plants. Voracious feeders that can lead to reduced growth, die back and in really   severe cases death of stressed plants
  • Attack - poplar, apple and many other ornamentals

Gall Insects and Mites
small insects 
  • Cause formation of galls - felty bumps of the leaf surface, petiole or stems. 
  • Rarely cause serious damage - more aesthetic
  • Attack - poplar, elm and other woody ornamentals
Leafhoppers

small, slender pale green, yellow or white insects that hop

  • Sap-sucking insects that cause bleaching or mottling of leaves.  Sometimes the leaves turn brown and curl up at the edges.  Plants may become stunted with a decline in plant vigour
  • Attack - Virginia Creeper, roses, annuals and perennials
Leaf Beetles

small brown or black and yellow insects

  • Found in clusters on the undersides of leaves; chew holes in leaves or skeletonize them
  • Attack - poplar, willow
Lilac Leaf Miner

small flattened yellowish caterpillar

  • Mine between the leaf layers causing yellow or brown blotches; then exit, roll up the leaf from the tip and continue to feed causing skeletonizing of the upper leaf surface.  More of an aesthetic   problem.
  • Attack - lilac
Leaf Roller

green caterpillar with a brown head

  • Rolls itself up in the leaf to feed.  Chews  irregular holes in leaves, chews on buds, flowers and fruit
  • Attack - most woody ornamentals
Pear Slug

small, olive-green to blackish, slimy, slug-like worm

  • Feed on the upper and lower surfaces of the leaf.  Leaves are chewed between the veins, leaving a lacy, translucent layer of tissue that turns brown
  • Attack - Pear, Rose and other plant in the rose family
Rose Gall Wasps

wasplike insects

  • Lay eggs in stems of roses causing large swellings or galls.  
  • Attack - Roses
Sawflies

resemble caterpillars but have at least six pairs of legs; usually green with dark head and black or black and yellow stripes

  • Feed on leaves either skeletonizing leaves or feeding in from the edges
  • Attack - most woody ornamentals
Slugs

slimy black-brown speckled mollusks

  • Cause large irregular holes in leaves and gouging grooves in ripe and unripe fruit
  • Attack - most ornamentals and fruit
Spider Mites

tiny, rounded, eight-legged insects

  • Puncture foliage and suck plant sap; foliage becomes stippled yellow and looks dirty.  A fine webbing may be present
  • Attacks - all ornamentals
Thrips

tiny, slender, pale yellow, green or brown insects

  • Feed by rasping plant tissue then sucking the released plant sap.  The injured tissue dies, producing dead spots, distorted blooms and leaves and balled flowers.  
  • Attack - most ornamentals
Western Ash Bark Beetle

small brown-black beetles; white legless grubs

  • Larvae chew tunnels in the cambium layer under the bark causing a disruption in  nutrient flow; branches and trunks may be girdled and die
  • Attacks - Green Ash
Wood Borers

white legless larvae mature into beetles or moths

  • Larvae bore into the sapwood of the tree.  External symptoms - holes in bark through which insects expel sawdust-like excrement, young branches may wilt death of branches or the whole tree.
  • Attack - willow, poplar, birch, elm, ash and many more

Fruit Pests

Currant Fruit Flies

legless white larvae

  • Develop within the fruit which turns red and drops prematurely
  • Attack - currant, gooseberry, Saskatoon
Imported Currantworm

yellow and black sawflies

  • Feed on foliage - can completely defoliate shrubs in the spring
  • Attack - currant, gooseberry
Leaf Rollers

greenish-white caterpillars with a brown head

  • Feed on fruit, buds and leaves.  Leaf in rolled together and fastened with silk, larvae live and feed within the rolled leaf
  • Attack - most fruit
Raspberry Fruitworm

tiny brown beetles

  • Feed on emerging foliage, damaging foliage, buds and blooms.  Wormlike larvae tunnel into flower buds and developing fruit.  May cause reduce yields
  • Attack - Raspberry