What's Bugging Your Evergreens

Insect Pests

aphids on evergreens


Plants affected:  Numerous indoor and outdoor plants


Symptoms:  Severe infestations will cause curling/twisting of foliage, flowers to wilt and drop


Life Cycle:  Eggs hatch on host plants in spring, these nymphs give birth to ‘daughters’, within days the daughters give birth – up to 30 generations per summer


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


Chemical Control:  Doktor Doom House and Garden, End All

Pine False Webworm

Pine False Webworm

Plants Affected – Pine


Symptoms – Silken feeding tubes filled with needles, frass and cast skins


Life Cycle:
Overwinter as larvae in soil beneath tree
Adults emerge in spring, mate and female lays egg on last year’s needles
Larvae hatch in 2 weeks, crawl to base of needle and feed
Larvae create tubes along branch from within which they feed
Feeding complete by late June when larvae drop to ground to overwinter


Cultural Controls – Remove larvae by hand


Chemical Controls:  Malathion and BTK

Pine Needle Scale

Plants Affected – White/Colorado Spruce, Scot’s/Lodgepole Pine, Douglas Fir and other Spruce



  • As scale feeds, yellow/green spots develop on needles
  • Branches take on unhealthy grey appearance
  • Scales are white, appear as flecks of white paint on needles

Life Cycle: Overwinter as eggs underneath the scale hatch in spring and move to other needles and hosts.  Mating and egg laying occur in August


Controls – Chemical:
Malathion – apply shortly after new growth appears in early or Mid June
• Can re-spray in early August before females form their hard shell

Pine Tortoise Scale

Plants Affected – Mostly Scots, Jack and Austrian Pine



  • Scales resemble tiny tortoises up to 1/4″ long.  Appear on 1-2 year shoots
  • Severe infestations result in decreased plant vigor, sooty mold from honeydew secreted by the insect

Life Cycle:  Immature females overwinter, resume growth in spring, mature in June.  Eggs are then laid beneath female, up to 500 each!


Controls – Cultural or Non-chemical:  Prune away damaged stems


Controls – Chemical:  Malathion – apply shortly after new growth appears in early or Mid June, when immature crawlers are active.

Spider Mite on evergreens

Spider Mites

Plants affected:  Spruce, Pine


Affects lower and center of tree
• Webbing – very fine
• Appears in hot, dry weather


Life Cycle:
• Adults come out of dormancy in spring
• Lay as many as 100 eggs in 2 week lifespan. Eggs hatch anywhere from 5-25 days
• Several generations per season. In fall, their exteriors harden, go into hibernation, can survive very harsh winters


Cultural Control:  Strong jet of water


Chemical Control:  Malathion and Ambush

Spruce Budworm

Spruce Budworm

Plants Affected – Spruce


• Lots of feces, webbing
• Insect has a brown/black head—so as not to confuse it with yellowheaded spruce sawfly. Young larvae are yellow green bodied, older cinnamon brown bodied


Controls – Cultural or Non-chemical:
Handpick small infestations
• Have some natural predators


Controls – Chemical:  Malathion and Ambush

Spruce Gall Adelgid

Spruce Gall Adelgid

Plants Affected – Spruce, Douglas Fir


Damage cosmetic
• Early spring white fluff may occur, followed by galls
• Damage is usually 8’ or lower


Controls – Cultural or Non-chemical:
Hose down white fluff
• Hand prune galls (green/purple ones still have adults inside)


Controls – Chemical:  Watch for female nymphs feeding in early spring; spray with Malathion

Western Tussock Moth

Western Tussock Moth

Plants Affected – Many trees/evergreens


Needles are chewed, leaving little stubs
• Primarily feed on newer growth closer to tops of tree, then down
• Caterpillar is furry, two long black antennae and 4 distinct furry tufts on top of body. Brightly coloured spots


Life Cycle – Overwinter as eggs, emerge in spring and start feeding. Mate, hundreds of eggs are laid and larvae stages feed heavily


Biological Control – BTK


Chemical Control – Need to monitor early in season, if large populations occur, spry with Ambush

White Pine Weevil

White Pine Weevil

Plants Affected:  Pine


• Possible resin leaking
• Punctures capped w/black near top of leader
• In late June/July, drooping/wilting, shepherd’s crook at top
• Emergence holes from adults seen after this


Life Cycle:
• Adults emerge in early spring, lay eggs in leader
• Larvae then feed downward
• Cocoons form in late July, then adults emerge Aug-Sept


Cultural Controls:
• Remove leader
• Trees must be kept healthy (well watered)


Chemical Controls:  None

Spruce Sawfly

Yellowhead Spruce Sawfly

Plants Affected – Spruce


• Clean cut needles, strong resin scent
• Feed on new needles first ‘clean feeders’
• No webbing, feces


Life Cycle:
• Adults emerge from ground in late May, lay eggs at base of needle
• Eggs hatch 5-10 days later, feed for 30-40 days
• At maturity, drop to ground, form cocoon


Cultural Controls:
• If infestations small, hand pick
• Strong jet of water


Chemical Controls:  Ambush and Malathion


Cytospora Canker

Plants affected: Evergreens


• Needles start off yellow, in summer turn purple
• During periods of wetness, gelatinous threads can be seen
• Cankers form with sunken ridges, girdle branches, cause dieback


Life Cycle: Secondary fungal disease – moves in on sun scalded wood, stressed trees


Cultural Control:
• Pruning
• Keep trees healthy and well watered


Chemical Control: None

Juniper-Hawthorn Rust

Juniper-Hawthorn Rust

Plants Affected: Juniper/Cedars, and Hawthorn, Crabapple, Apple, Mountain Ash


Symptoms and Life Cycle
• Galls form on juniper/cedar branches
• After spring rains, galls ooze gelatinous ‘spore horns’
• On alternate hosts (hawthorn, etc.), yellow-orange spots show, later become orange-yellow surrounded by red bands. These will then release spores in June/July, infecting junipers/cedars in the area


Controls – Cultural or Non-Chemical:
• Eliminate a host (note: neighbours could still have one of the hosts)
• Prune out juniper galls in late winter/early spring before spore horns emerge
• Keep plants well-watered and fertilized


Controls – Chemical:  Copper fungicide (Bordo) should be sprayed on Hawthorns and other alternate hosts foliage as plants start to bloom, then repeated twice at 7-10 day intervals

needle cast

Needle Cast

Plants Affected: Spruce trees


• Mimics winter injury
• Starts as light green to yellow spots, which turns to brown or red
• Black spores will be seen on needles prior to drop (early spring)


Life Cycle:  Fungus, spores infect new growth, damage appears next spring


Cultural Controls: Keep trees healthy and well watered


Chemical Controls: None

Sirococcus Tip Blight

Sirococcus Tip Blight

Plants affected: Spruce (Colorado, white, Norway) and Pine (Mugo, Scots, Jack)


• Browning, wilting, curling of young shoots, most often on lower growth
• Infected shoots have a hooked appearance and eventually lose all needles
• Small purplish cankers may appear on current year growth


Life Cycle: Overwinters on infected plant material, cool wet springs facilitate the spread of the disease onto new or current year’s growth


Cultural Controls: Remove and destroy affected needles/shoots on a regular basis


Chemical Controls: Copper spray starting mid June at 10 day intervals

Cultural Disorders

frost damage on evergreen

Evergreen Winter Damage

• winter winds, light reflecting off snow cause needles to brown, die off
• sometimes symptoms not seen until spring, if damaged primarily on south side of plant this is sunscald


• ensure proper placement of susceptible plants (cedar, boxwood, long needle pine)
• plants should be thoroughly watered prior to final freeze up in autumn



• very common on fruit trees, especially cherries


• causes vary from mechanical damages such as sapsucker damage, squirrel damage, wood boring insects or delayed winter injury, which is common in fruit trees
• beyond avoiding these, let the wounds heal over on their own

Herbicide damage on evergreens

Herbicide Damage

• curling or cupping leaves
• discoloration between veins
• twisted, elongated stems


• use all herbicides according to label, note that herbicide can drift for several miles, it’s very difficult to ascertain where chemical drifts from
• keep damaged plants well-watered, most plants will recover

Overwatered evergreen


• wilting, yellowing leaves
• leaves will yellow from outside in
• Note: wilting is a symptom of BOTH over and underwatering, if plants are wilting don’t assume they require moisture until soil is checked by hand


• plants in lower lying areas will suffer in times of heavy rains; plant appropriate species in these areas
• for new and established plants, water only as required; check soil prior to watering

underwatering evergreens


• wilting, crispy or browned leaf edges


• water, especially for new transplants should be monitored daily during periods of extreme heat
• for new transplants, stick your hand into the soil to determine if moisture is required