Article author: Ballinger (Vacant)
Most recently reviewed by: Danielle Sekula & Tyler Mays (2021)

Common Name(s): cherry vinegar fly, Spotted wing drosophila

Description

The spotted wing drosophila (SWD) is a fruit fly that is a 1/16 to 1/8 inch long with red eyes and a yellow-brown thorax and abdomen. There are black stripes down its abdomen. The adult males have a single black spot on the tip of each wing, but the females lack this distinctive marking, making it difficult to identify this insect.

The adults and larvae closely resemble the common vinegar fly, D. melanogaster, as well as other Drosophila species that attack mostly rotting or fermenting fruit. However, the SWD prefers healthy, ripening fruits.

Origin and Distribution

The spotted wing drosophila is native to Asia and is found throughout most of the fruit producing states in the U.S. The distribution map below shows counties in which SWD has been reported using EDDMaps. If you find SWD in your area, please consider reporting to EDDMaps.

Habitat & Hosts

The spotted wing drosophila prefers healthy, ripening fruits. They are commonly found on thin-skinned, soft fruits such as strawberries, blackberries, raspberries, blueberries, cherries, and plums. They can also be found on apples and pears, but only if these fruits become damaged. SWD have also been found on other hosts such as mulberry and honeysuckle.

 

Life Cycle

The spotted wing drosophila can complete its life cycle in 1-2 weeks, depending on environmental conditions. SWD are most active at temperatures above 68°F, but will decrease laying eggs in temperatures above 86°F. The SWD can have multiple generations per year and females can lay up to 300 eggs in her lifespan.

The female SWD penetrates the skin of the fruit with her serrated ovipositor and lays her eggs under the skin, causing a small puncture or “sting”. A female can lay 1-3 eggs in these puncture sites and they will hatch in 2-72 hours. The larvae tunnel and feed inside the fruit for 5-7 days. They then pupate inside or outside the fruit which lasts from 3-15 days and emerge as adult flies. The SWD overwinters as adults.

The damage from SWD is initiated when the females use their ovipositor to cut through the fruit skin leaving a small scar that is sunken in. The damage is primarily done by larval feeding which causes the fruit to turn brown and soft. This causes the fruit to collapse due to internal rots and damage caused by mold or secondary infections.

Management

If you live in the State of Texas, contact your local county agent or entomologist for management information. If you live outside of Texas, contact your local extension for management options.

In order to determine if you have SWD present, monitor your garden for adult flies as soon as the fruit starts to set until the end of harvest. The most important time to monitor is when fruit color first starts to develop until harvest.

There are some cultural control practices that can help reduce the buildup of SWD populations. Removing any infested or overripe fruit, wild host plants such as mulberries and grapes nearby your field or garden, and ensuring a timely harvest are all important in reducing SWD populations. Early harvest of fruit can be important in reducing the exposure of fruit to the SWD. Begin harvest as early as you can and continue to remove fruit as they ripen. Another example of a cultural control method that can be used to manage SWD is the use of netting or floating row covers. The covers prevent SWD access to developing fruits and can potentially reduce the infections.

Since the SWD will complete multiple, overlapping generations, there is continuous activity once the flies become active. The insecticides only target the adults and will not control the larvae already in the fruit since they are protected by the fruit. Insecticides used for SWD include organophosphates and synthetic pyrethroids, as well as spinosyn but it has shown lower activity and residual control. It is important to read and follow the label restrictions of insecticides applied if you to intend to consume or sell what you harvest.

Citations

Caprile, J.L., Flint, M.L., Bolda, M.P. Spotted Wing Drosophila. University of California Statewide IPM Program: Pest Notes 74198. http://ipm.ucanr.edu/PDF/PESTNOTES/pnspottedwingdrosophila.pdf

Carroll, Juliet. 2017. Spotted Wing Drosophila. New York State Integrated Pest Management Program- Cornell University. https://ecommons.cornell.edu/bitstream/handle/1813/42883.3/spotted-wing-drosoph-NYSIPM.pdf?sequence=6&isAllowed=y