Spotted Wing Drosophila

Drosophila suzukii


Spotted-wing drosophila, Drosophila suzukii (SWD) is an invasive vinegar (AKA fruit) fly.  It attacks many soft summer fruits, including stone fruits, cherries, cane fruits and grapes as they ripen. Unlike other fruit flies which are attracted to damaged and overripe fruit, SWD attacks undamaged fruits. The female uses her serrated ovipositor to puncture the fruit flesh and deposit her eggs. Some fruits like raspberries and blackberries show little to no evidence of infestation until the fruit is completely ripe.

SWD has spread rapidly since its first detection in the US in the mid-2000’s and is now present in more than half of the states.  It was first detected in Colorado, in Ft. Collins, in 2012 and in other northeastern Colorado counties in 2013.

Drosophila larvae (not suzukii) found in
raspberries grown in western CO in 2013.

SWD trap Cherries, raspberries, and grapes within the upper Grand Valley were monitored for SWD presence during the summers of 2010-2013 using modified red plastic drinking cups and apple cider vinegar bait. Traps were initially placed in cherry orchards and the cane fruits and then grape as the crops matured. Ten or more traps were set out in each fruit type. Traps were checked weekly. Several species of fruit flies were captured, but no SWD were found in the traps until October 2014 when SWD flies were trapped at two sites on central Orchard Mesa.  It is very possible that SWD is present in back yard, garden and commercial can fruits within the Grand Valley.

No SWD have been found to date in traps located in the North Fork Valley of Delta County or in the Olathe area of Montrose County.

Go to for the most up to date information on SWD biology and management research.

Other Links
Utah Pests Fact Sheet
Bulletin from Michigan State University
Oregon State University Fact Sheet

UMass Amherst-SWD Identification and Control

This page was updated on January 30, 2015