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Ministry of Agriculture, Food and Rural Affairs

Spotted Wing Drosophila

Spotted wing drosophila trap in a peach tree Spotted wing drosophila Spotted wing drosophila Spotted wing drosophila damage End of spotted wing drosophila Spotted wing drosophila larva Spotted wing drosophila trapClick to enlarge.

Beginner

This pest affects:

Peach Apricot Plum Sweet Cherry Tart Cherry ;

Scientific Name 
Drosophila suzukii

Identification
Adults

  • Small (2-3 mm), red-eyed fly with a pale yellow or brown abdomen marked by dark brown unbroken bands or stripes
  • Males have a distinct black spot towards the tip of each wing (spots not visible in newly emerged males)
  • Females lack the spots on the wings, but have a saw-like ovipositor which is used to cut into fruit for egg-laying

Larvae

  • Tiny (up to 6 mm), white, cylindrical and generally featureless maggots that can be found feeding in fruit
  • A single fruit may be infested with multiple maggots
  • After maturing, the larvae partially or completely exit the fruit to pupate

Pupae

  • 3 mm in length, brown, and have two stalks with small finger-like projections on one end

Injury

  • Eggs and larvae in intact fruit prior to harvest may result in rejected loads
  • Eventually, fruit softens in spots and the skin collapses, with a wrinkled appearance that becomes very obvious after about 5 days

Often Confused With
Common vinegar fly adult:  bands of colour on body are not unbroken; males do not have spot on wing; females do not have large serrated ovipositor

Cherry fruit fly adult:  larger (5 mm) and have a dark banding pattern on their wings; females do not have large serrated ovipositor

Common vinegar fly and cherry fruit fly larvae:  difficult to distinguish from SWD:  must be reared to adult for identification; vinegar fly larvae found only in injured or overripe fruit

Period of Activity
Pre-harvest. 

Threshold
No thresholds established. 

Scouting Notes 
Monitoring for spotted wing drosophila should include the use of baited traps to collect adults and examination of susceptible fruit near harvest for the presence of larvae.

 Traps can be constructed of plastic containers with lids. Perforate the containers with small holes (0.5 cm) to allow entry of spotted wing drosophila flies and prevent trapping of larger species. Bait traps with a small amount of apple cider vinegar, and check them regularly. Place traps when the temperature is consistently over 10°C, and/or when fruit starts to form, at least one month prior to fruit ripening. Once fruit begins to ripen, flies are less likely to be attracted to traps.

Traps should be placed in sheltered areas near field edges or in hedgerows, particularly if wild hosts are present. Traps have limited value in predicting the presence of SWD as early-warning monitoring tool, particularly early in the season. By the time flies are caught in traps, infestation of fruit may have already begun. Numbers in traps increase dramatically in late summer, following harvest. Suspect infested fruit can be collected and larvae reared to adults for identification purposes.

 

Advanced

This pest affects:

Peach Apricot Plum Sweet Cherry Tart Cherry Pear;

Scientific Name 
Drosophila suzukii

Identification
Adults

  • Small (2-3 mm), red-eyed fly with a pale yellow or brown abdomen marked by dark brown unbroken bands or stripes
  • Males have a distinct black spot towards the tip of each wing (spots not visible in newly emerged males)
  • Females lack the spots on the wings, but have a saw-like ovipositor which is used to cut into fruit for egg-laying

Larvae

  • Tiny (up to 6 mm), white, cylindrical and generally featureless maggots that can be found feeding in fruit
  • A single fruit may be infested with multiple maggots
  • After maturing, the larvae partially or completely exit the fruit to pupate

Pupae

  • 3 mm in length, brown, and have two stalks with small finger-like projections on one end

Injury

  • Eggs and larvae in intact fruit prior to harvest may result in rejected loads
  • Eventually, fruit softens in spots and the skin collapses, with a wrinkled appearance that becomes very obvious after about 5 days

Often Confused With
Common vinegar fly adult:  bands of colour on body are not unbroken; males do not have spot on wing; females do not have large serrated ovipositor

Cherry fruit fly adult:  larger (5 mm) and have a dark banding pattern on their wings; females do not have large serrated ovipositor

Common vinegar fly and cherry fruit fly larvae:  difficult to distinguish from SWD:  must be reared to adult for identification; vinegar fly larvae found only in injured or overripe fruit

Period of Activity
Pre-harvest. 

Biology
The female spotted wing drosophila has a heavily serrated ovipositor that allows her to saw through intact fruit and lay her eggs under the skin. Larvae hatch and feed on the fruit, rendering it unmarketable. Disease pathogens and other insect pests can also enter through the egg-laying holes, causing further deterioration of the fruit.  The spotted wing drosophila will attack thin-skinned fruit such as raspberry, blackberry, blueberry, strawberry, cherry, plum, peach, nectarine, and sometimes grape.

In other temperate climates, the spotted wing drosophila overwinters as an adult in protected areas, including heated buildings and heated foundations. They move back into host crops in the spring. There can be multiple overlapping generations each year. Adults become active in the spring, with damage occurring to fruits as they begin to ripen throughout the growing season.

Threshold
No thresholds established. 

Scouting Notes 
Monitoring for spotted wing drosophila should include the use of baited traps to collect adults and examination of susceptible fruit near harvest for the presence of larvae.

 Traps can be constructed of plastic containers with lids. Perforate the containers with small holes (0.5 cm) to allow entry of spotted wing drosophila flies and prevent trapping of larger species. Bait traps with a small amount of apple cider vinegar, and check them regularly. Place traps when the temperature is consistently over 10°C, and/or when fruit starts to form, at least one month prior to fruit ripening. Once fruit begins to ripen, flies are less likely to be attracted to traps.

Traps should be placed in sheltered areas near field edges or in hedgerows, particularly if wild hosts are present. Traps have limited value in predicting the presence of SWD as early-warning monitoring tool, particularly early in the season. By the time flies are caught in traps, infestation of fruit may have already begun. Numbers in traps increase dramatically in late summer, following harvest. Suspect infested fruit can be collected and larvae reared to adults for identification purposes.

Management Notes
Remove wild hosts (possibly choke cherry and brambles) to help reduce populations.

Be aware of infestations in neighbouring vineyards, orchards and berry plantings, as well as unmanaged areas and backyards where alternative hosts are present.

There are no insecticides registered for spotted wing drosophila in Ontario. If it is detected consult OMAFRA specialists.  Some insecticides that are applied for other orchard insects may provide control of spotted wing drosophila.