A University of Florida study found that a yeast-sugar-water mixture lures spotted wing drosophila flies better than apple cider vinegar.
The project also looked at adding a yellow visual stimulus to the trap, such as yellow tape or a yellow card, to improve fly catches. The simple answer: No, lures with and without yellow caught about the same number of flies, according to a news release.
The study, conducted by entomology doctoral student Lindsy Inglesias, entomology and nematology professor Oscar Liburd and post-doctoral fellow Teresia Nyoike, examined different lures and trap colors.
Nationwide, some experts have recommended using apple cider vinegar as a lure because of its simplicity. Others have contended that a yeast-sugar-water mixture does a better job catching flies.
SWD traps typically are made from clear 32-ounce plastic drink cups that come with a lid.
Holes are punched near the upper rim of the cup, and a lure is poured in about 1 inch deep. A drop of dishwashing liquid is added to thicken the bait and keep insects from escaping.
Growers typically check the traps weekly, emptying the liquid and replacing it with fresh bait.
During one experiment in 2012 and 2013, the researchers compared plastic cups with and without yellow cards placed inside and found no difference between the two treatments.
The theory was that yellow attracts many insects, and that's why it's used on yellow stick cards.
In this case, the spotted wing drosophila didn't seem to prefer yellow.
During the research, they also found that cups with the yeast-sugar-water bait caught more SWD than those with apple cider vinegar.
But the yeast-sugar lure has its drawbacks—it stinks and is cloudy, making it harder to see the insects, especially after they've been sitting in it for a week.
Nevertheless, UF experts recommend the yeast-sugar-water bait because it catches insects quickly, giving growers the information faster so they can get a jump on the pest.
They recommend two traps per acre.
For more information, including instructions on how to build traps and mix the lure, visit http://edis.ifas.ufl.edu.