Chow Line: A tiny worm in your strawberry won’t hurt you

Writer(s): 
Tiny white larvae in a strawberry caused by spotted wing drosophila. Photo courtesy of Hannah Burrack, North Carolina State University, Bugwood.org.

I just saw a viral video that shows little tiny worms coming out of a strawberry soaking in salt water. Is that real or a prank? Can I get sick from eating strawberries if they do have worms?

Many people in recent weeks have been surprised to learn that yes, sometimes fresh produce can contain small pest infestations that, while may sound gross to some, really aren’t harmful for consumers. 

In fact, there is a strong likelihood that you’ve already unknowingly consumed a tiny worm or insect or two during your lifetime. 

The Food and Drug Administration has guidelines for how many bugs or how much mold is allowed in each type of food. Using what the FDA calls food defects standards, the agency sets the maximum levels of natural or unavoidable defects that present no health hazards in foods for human use. 

This is because, “it is economically impractical to grow, harvest, or process raw products that are totally free of nonhazardous, naturally occurring, unavoidable defects,” the FDA says.

For example, berries are allowed to have an average of four or more larvae per 500 grams, the standards say. And 14 ounces of tomato juice is allowed to have up to four larvae and 20 or more fruit fly eggs, while even a chocolate candy bar is allowed to have 60 or more insect fragments per 100 grams when six 100-gram subsamples are examined, the FDA guidelines say.

Even though that may sound gross for some, the tiny white larvae that can sometimes be found inside strawberries are harmless to consumers. They are actually the larvae of a fly, commonly known as the spotted-wing drosophila, an invasive species of pest from East Asia that infests berry crops and was first seen in the United States in 2008, said Celeste Welty, an Ohio State University Extension entomologist and associate professor of entomology. 

OSU Extension is the outreach arm of The Ohio State University College of Food, Agricultural, and Environmental Sciences. 

The pest, which has been found in Ohio since 2011, can be a problem for berry growers because it can cause significant crop damage. But, if spotted early, it can be managed to avoid losses, Welty said.

Spotted-wing drosophila targets fruit crops, including raspberries, blackberries, blueberries, grapes, peaches, and plums, and sometimes cherries, strawberries, pears, apples, and cherry tomatoes. The pest causes damage through larval feeding on ripening fruit. Damage starts as a tiny scar on the skin of the fruit, with the skin collapsing in two or three days and mold developing.

“The consensus is that they almost never infest traditional June-bearing strawberries, but they often attack ever-bearing strawberries later in the summer, both in field plantings and in high tunnels,” she said.

Thanks to training offered by OSU Extension on spotted-wing drosophila, more fruit growers now know how to manage the fly to lessen the potential for it to infest fruit crops, Welty said. That often includes spraying a weekly insecticide on the crops through the end of harvest and monitoring when the insect comes onto their farm and preventing females laying eggs in the fruit, or enclosing the crop under fine-mesh netting.

Consumers can determine if the fly larvae are in a piece of fruit by putting the fruit in a plastic zippered storage bag or a one-quart container filled with warm, salty water and waiting 15 minutes, Welty said. 

“The bags or container with infested fruit will show little larvae floating to the top of the salt water,” she said, noting that if any appear, they are harmless.

“For those who may be squeamish about larvae, locally grown berries harvested in June are less likely to have larvae,” Welty said. “This is because the spotted-wing drosophila typically does not become active until July.”

Chow Line is a service of The Ohio State University College of Food, Agricultural, and Environmental Sciences and its outreach and research arms, Ohio State University Extension and the Ohio Agricultural Research and Development Center. Send questions to Chow Line author Tracy Turner, 364 W. Lane Ave., Suite B120, Columbus, OH 43201, or turner.490@osu.edu.

Editor: This column was reviewed by Celeste Welty, an OSU Extension entomologist and associate professor of entomology.

For more information contact: 
Tracy Turner
614-688-1067
Source(s): 

Celeste Welty
614-292-2803
welty.1@osu.edu