Spotted wing drosophila
Click to enlarge.
Beginner
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
- 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
- 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: found only in injured fruit; bands of colour on body are not unbroken; males do not have spot on wing; females do not have large serrated ovipositor
Period of activity
Pre-harvest. Spotted wing drosophila will move into varieties sequentially as they ripen. Grapes are at risk of attack by spotted wing drosophila as they begin to ripen and up until 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.
Simple 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
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
- 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
- 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: found only in injured fruit; bands of colour on body are not unbroken; males do not have spot on wing; females do not have large serrated ovipositor
Period of activity
Pre-harvest. Spotted wing drosophila will move into varieties sequentially as they ripen. Grapes are at risk of attack by spotted wing drosophila as they begin to ripen and up until 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.
Simple 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 of over-ripe or dropped fruit from the vineyard and bury.
Removal of wild hosts (possibly choke cherry and brambles) will 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 vineyard insects may provide control of spotted wing drosophila.
