Insect and Mite Pests of Strawberries

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  Aphid | Clipper weevil | Leaf rollers | Mites | Slugs | Spittle bug | Strawberry root weevil | Tarnished plant bug | Wasps/yellow jackets/hornets

An important part in the production of any fruit crop is to know what type of insects could cause production losses. A crop is at risk throughout the fruiting cycle. Insects can attack plants during flowering, fruit formation or just before harvest of the plump, juicy berries. A successful pest management program includes: insect identification; pest number and damage monitoring; what population numbers warrent control and knowing when the pest can be effectively controlled.



  • the aphid is 1-3 mm long, soft-bodied and pear-shaped
  • main identifying feature: cornicles (tailpipes sticking out of the back end)
  • variety of colors: green, yellow, pink, white, bronze, dark-brown or black
  • adults can be winged or wingless

Green Peach Aphid

Life cycle
  • overwinters as egg on the host plant
  • hatchs into a "stem" mother and starts bearing live young; which, in turn, bear live young
  • each mature aphid can produce 50-100 offspring
  • 15-30 generations produced per season
  • aphids can reproduce either sexually or asexually, males are not produced until fall; mating occurs and either an egg or another stem mother is produced which lays the overwintering egg
  • moist, cool weather favors aphid outbreaks

  • feeding symptoms include: leaf discoloration, flattened appearance, shiny (from honey dew) and, in severe cases, wilted plants
  • produces a sticky substance called honey dew; makes the leaves and fruit sticky and can promote the growth of sooty mold fungi (not harmful to the plant but both can make the fruit unsalable)
  • it seldom causes much direct injury, unless present in large numbers
  • can transmit viral diseases

  • generally, they are found in clusters on the new growth, stems, buds or on underside of leaves
  • in young plants, aphids may cluster near the base of the plant
  • look for symptoms weekly
  • severe infestations are often visible from the edge of the field
  • economic threshold--30 aphids per plant
  • before spraying consider: weather conditions, presence and abundance of natural enemies, value and stage of the crop

Cultural control
  • start with clean stock
  • there are a wide range of natural predators: lady bugs, lace wings, and predatory wasps

Clipper Weevil

  • 2-3 mm long, dark reddish-brown weevil
  • it has rows of tiny pits and two small white spots with dark centers on its back
  • the long snout is about as long as the insect's body
  • the legless larva is 2 mm long, white to yellow white, thick bodied and curved

Life cycle
  • the female inserts a single egg inside an almost mature bud and then girdles the bud to prevent it from opening and exposing the larva
  • in 1 week, the egg hatches
  • adults emerge in late June; and, in few weeks, they seek a hibernation site, remaining there until the following spring

  • holes in flowers and petals
  • stems that are chewed or almost clipped through and left dangling
  • the dead straw-colored section is easy to see against the green of the plant

  • weekly checks beginning in May with the early-blooming varieties
  • first place to look--closest to woodlots and shelterbelts
  • economic threshold is one or two clipped buds per metre of strawberry row
  • more information on monitoring for the clipper weevil is described in the Ontario Ministry of Agriculture and Food,Agdex 232/620 Strawberry Clipper Weevil: A Major Pest of Strawberry.

Cultural control
  • minimize the amount of trash in the fields in mid to late summer
  • separate new plantings from old
  • vigorous tillage of old beds after the final harvest while the clippers are pupating will reduce the movement of clippers from infested fields to non-infested fields

Leaf Rollers

  • a diverse group of moths
  • the caterpillar is slender, green to brown, 12 mm long with dark-brown or black head
  • very active and moves backwards when disturbed

Life cycle
  • the eggs are laid on the strawberry leaves
  • larvae change from pale green to greyish brown as they mature
  • they pupate rolled in the leaf
  • could be 2 generations per year

  • holes are eaten in the leaves; later the leaves are folded in half and webbed together, causing the leaves to turn brown and die
  • the fruit is rarely attacked
  • damage is usually minimal
  • damage is most common on new plantings late in the season

  • start in the spring
  • look for the folded or rolled leaves, also discolored leaf areas showing some feeding damage
  • unroll leaves and look for small green caterpillars
  • if no caterpillar, then the insect is gone
  • economic threshold--spraying is seldom necessary as healthy strawberry plants have an abundance of leaves and the loss of a few leaves has little effect on fruit production

Cultural control
  • there are several natural predators and parasites that do keep the populations in check
  • spraying is difficult; as once the leaves are rolled, the insect is protected


  • the cyclamen mite (CM) is oval, semi-transparent,.25 mm long, shiny and light-green, amber or light tan colored, the nymphs are milky-white; the females are pale-brown
  • the spider mite (SM) is .5 mm, oval, greenish-yellow with 2 irregular dark spots on back

Spider Mite

Life cycle
  • CM overwinter as egg, nymph or adult on underside of leaf, close to the ground
  • CM lay eggs in dark moist places on the host plant (buds and leaf clusters), several generations can overlap
  • each female can produce up to 90 eggs; 80% develop into females
  • SM overwinter as adults
  • when the plant starts to grow, mites mate and lay eggs
  • the eggs hatch and begin to feed
  • there can be several generations overlapping
  • hot, dry weather favours population explosions of SM (depending on the species)

  • CM--feeding reduces vigour of plants
  • growth appears retarded, twisted, and distorted
  • stems and petioles of leaves remain short and do not elongate
  • high infestations cause new leaves to form a compact mass in crown centre
  • at this point, the leaves are usually brownish green
  • in high infestations, CM move out to feed on the flowers, causing flower death; fruits are small, dry and distorted, and the seeds stand out on the berry
  • symptoms are apparent, even at low population levels
  • SM feed on the leaf underside, preferring the young leaves in the crown
  • feeding damage causes yellow spots (mottling or stippling), leaf crinkling, browning and leaf curling
  • high populations will cause loss in plant vigor and fruit will not form

  • CM--check the midrib of leaflets where they join the petiole
  • economic threshold--10-15 mites per leaf, densities of 45-65 mites per leaf can reduce yield by 33%
  • SM--examine for webbing between or under the leaflets, damage shows up in dry areas of field
  • diagnostic tool--breathe on leaflets, this causes the mites to scurry about; or, tap the leaf over a white sheet of paper, making the pest visible
  • economic threshold is 5 mites per leaf before July 30

Cultural control
  • CM control is hard because the mites hide in closed leaf and flower clusters where the penetration of a pesticide is almost impossible
  • SM predators become established as a strawberry planting matures
  • irrigate regularly to avoid water stress on the plants
  • eliminate weeds that can also be hosts
  • cultivate in the fall to disturb the overwintering sites
  • SMs have naturally occurring predators


  • slugs are 5-7 cm long, greyish, grey-brown or almost black in color, depending on the species and age of the gastropod
  • they hide during the heat of the day in moist-dark places like soil crevices, earthworm holes or under leaves

Life cycle
  • overwinters as adults in trash and leaf litter of hedge rows and windbreaks
  • slugs have both male and female sex organs (hermaphrodites)
  • mating usually takes place; but, under extreme situations, they can fertilize themselves
  • eggs are oval clear, cream or yellow, up to 3 mm long and are in batches of 20 or more
  • the eggs can lay dormant until sufficient moisture is available because they are protected by a jelly like substance
  • eggs can be produced at anytime during the growing season.

  • can be serious in wet areas or through out over-irrigated fields
  • most damaging to young plants, but can contaminate fruit by feces and slime
  • most pickers either will not pick or will toss away slug contaminated fruit
  • foraging is done in a relatively small area and they usually return to the same spot to hide during the day, unless this spot dries out
  • feeding produces large ragged holes; they rasp away the plant tissue, then suck up the residue
  • feeding is done at night, most active 2 hours after sunset to 2 hours before sunrise, especially when the temperature is below 23°C.

  • watch for slime trails and shredded leaves
  • they can be found resting or hiding when populations are high

Cultural control
  • predators--ducks, chickens, garter snakes, toads and salamanders
  • insect predators--ground beetles, soldier beetles, centipedes and rove beetles
  • prevention is the best method of control
  • limit excessive straw use, vigorous tilling at renovation also helps
  • avoid planting in perennially wet spots
  • clean equipment when moving from a slug infested area to a clean area
  • remove the organic litter on the soil surface of the shelter belts

Chemical control
  • chemical controls are available; slug baits have been somewhat successful--follow label directions
  • till headlands and inter-row areas

Spittle Bug

  • protects itself by covering its body with a white, frothy spit like substance
  • it is 1-2 cm or more and resembles a fat aphid
  • nymphs are white to lemon yellow
  • adults are greyish-brown, 6 mm long
  • it can hop and fly

Spittle Bug Masses

Life cycle
  • overwinters as an egg in masses of 2-30 on lower parts of crown
  • eggs hatch in May
  • nymphs take 5-8 weeks to reach adulthood
  • adults migrate in June and return in September and October to lay their eggs

  • nymphs pierce the plant stems and suck plant juice
  • feeds at the base of the plants and later moves up into the developing foliage
  • excessive feeding causes distortion of leaves, shortened fruit spurs and small berries
  • plants will recover after the bug moves on

  • every 2 weeks, randomly select five 2 ft2 areas per acre
  • look for characteristic spittle at the base of plants in the crown area
  • nymphs will be at base of plant, so spreading the plant is necessary
  • some studies indicate that pick-your-own customers are willing to accept a spittle mass of about 2 masses per 2 ft2 without complaints
  • aesthetic threshold 1 froth mass per square foot

Cultural control
  • fields that had been hay or pasture in the rotation are at a higher risk for spittle bugs
  • with good weed control, they are less likely to return in the fall
  • weed free planting
  • populations are higher in fields surrounded with grasses and broad leafed plants like golden rod

Chemical control
  • experience indicates that when chemicals are applied for the control of tarnished plant bug, the spittle bug is controlled
  • spittle acts as protective covering, making chemical control hard; especially, if the spray coverage is poor and low water volumes are used

Strawberry Root Weevil

  • adult are 5-8 mm long, usually black, but can be light to dark brown, hump-backed and hard-bodied
  • wing covers have rows of round punctures and it can not fly
  • it has a blunt snout
  • larvae are 6 mm long, legless grubs, pinkish-white with a C-shaped body and brown head

    Strawberry Root Weevil adult

    Strawberry Root Weevil larvae

Life cycle
  • overwinters as adults and larvae under soil trash and around the base of host plant
  • emerge in late spring and early summer
  • migrate, looking for food hosts to lay their eggs beside
  • also migrate in the fall looking for overwintering sites (that is when most of us see them)
  • no males are known, each female can lay 200-300 small white eggs in soil cracks
  • in 2-3 weeks the eggs hatch, larvae burrow into ground and begin feeding on host plant roots

  • adult feeding causes a notching on the leaves
  • does little harm to plant but indicates the pest is there
  • grub feeds on the rootlets and can burrow into the main root weakening the plant, predisposing it to disease and winter injury
  • injured plants may wilt and die during dry summer periods

  • inspect the field edges every week or two during July and August, look for the notched leaf margins
  • a sweep net will help to collect the weevils for identification
  • in the fall, check for larvae by collecting stressed plants; slit open the roots and check for tunneling and larvae

Cultural control
  • cultivated soil around the field perimeter creates a barrier
  • crop rotation
  • remember, they have to walk through the field

Tarnished Plant Bug

  • adults are 5-6 mm long, 2.5 mm wide and flattened, pale green to reddish-brown with a distinct triangle or "V" mark 1/3 way down back
  • they are difficult to see because they fly or move rapidly
  • young nymphs are dull blue-green; look similar to aphids, but move faster and lack cornicles

Tarnished Plant Bug

Life cycle
  • adults overwinter under debris or plant cover along fence lines
  • in spring, they feed on early growing plants, mate and migrate to crops suitable for feeding
  • egg laying may be as early as mid-May (south) to mid-June (Peace country)
  • nymphs develop into adults in 12-34 days depending on the temperatures; the hotter the weather, the faster they develop
  • they are strong flyers

  • TPB punctures the plant tissue and sucks the juice when feeding
  • TPB punctures the seeds (usually in one area on the berry)
  • those seeds punctured abort and the hormone production of these seeds stops, as a result, the tissue around that area stops growing causing "cat facing" or "button berries" or "apical seediness"
  • hollow seeds (turn a brown color) distinguish TPB damage from poor pollination
  • generally, the earlier the feeding takes place, the more severe the fruit deformation
  • one nymph per inflorescence can result in 20-30% of the fruit being injured
  • tap a flower or a fruit cluster into a colored dish (any color other than white or green); the dish needs to be deep enough to allow for the insects to be trapped, but shallow enough to allow for inspection
  • how to monitor--tap 3 flower clusters into dish from 5 different locations in the field
  • if there are .5 nymphs per cluster, then it is time to spray
  • another method of monitoring for the TPB is described in the Ontario Ministry of Agriculture and Food Tarnished Plant Bug: A Major Pest of Strawberry Agdex 232/620.

Cultural control
  • get rid of weeds in and near strawberry plantings
  • mow permanent sod in the fall to prevent overwintering sites
  • the TPB moves into the berry crop when alfalfa fields near strawberry fields are cut

Wasps/Yellow jackets/Hornets

  • Yellow jackets and Hornets belong to the family of Wasps
  • Hornets are black with yellowish white markings and approximately 19 mm long
  • Yellow jackets are smaller and black with bright yellow markings
  • wasps are hunters and are useful in controlling caterpillars and flies, but they can become pests in the berry fields

Life cycle
  • warm, dry springs produce larger wasp problems in August than do wet, cool springs
  • in spring, a fertilized queen emerges from hibernation
  • she chooses a good nesting spot which could be in a hole in the ground (a mouse burrow), a tree branch, bush, under the eaves or in the walls of a building
  • the nest is built by chewing wood fibres into a pulpy mass
  • the queen lays eggs which hatch into legless, blind larvae
  • larvae last 2 weeks, then pupate
  • in 3 weeks, adult females emerge and begin to tend the queen
  • in August, male and new queen cells are produced
  • in early fall, the males and new queens emerge; mating takes place on the wing
  • males die and fertilized queens overwinter in protected sites like stumps or hollow logs
  • the old nest is abandoned and never used again

  • wasps are attracted to the ripe or injured fruit as a source of sugar and moisture
  • they can be dangerous to pickers because they sting, which is painful, and some people are allergic to the venom (which could result in death)
Cultural control
  • prompt harvesting of ripe berries and clean picking practices
  • hang a piece of meat or fish over a bucket of water with detergent in it, wasps will take a mouthful and fall into the water and drown
  • a 2 litre soda bottle with about 5 cm of soda left in the bottom attracts wasps into bottle
  • a basin with a few inches of water and syrup (like pancake) in it will attract the insect and it drowns in the water
  • set the nest on fire with a torch
  • knock the nest into a sack and burn it
  • carry out control methods after dusk, after the wasps have settled for the night
  • wear protective clothes (coveralls, gloves and hat netting with ends tucked into the collar)
  • if necessary to use a light, do not hold the flashlight, set it to the side and shine the light on nest
Chemical control
  • spray insecticide into the entrance of the nest, do this after dark
  • for ground nests, stuff insecticide soaked cotton or steel wool into the nest entrance
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For more information about the content of this document, contact Shelley Barkley.
This information published to the web on November 27, 2001.
Last Reviewed/Revised on November 24, 2008.