WEST OLIVE, Mich. — Friday marked the first day of U-Pick at Crossroads Blueberry Farm in West Olive, and traps are set for the Spotted Wing Drosophila.
"It's something that's not fun to deal with," said manager Luke DeHaan.
The Spotted Wing Drosophila (SWD) is a teeny-tiny fly that's as big as a nickel is thick (two-to-three millimeters). But the invasive species does more than five cents-worth of damage— try $700 million annually in the United States.
For Michigan— a state that picks 92 million pounds of blueberries every summer, ranking it third in the nation— that's an existential threat.
"If you do not do preventative maintenance...you will lose your crop," DeHaan said. "It's just a matter of time."
The mother fly does her damage when she lays eggs beneath the skin of soft fruits, depositing them with an organ called a serrated ovipositor.
"They'll go in and sting that berry," said DeHaan.
Days or even just hours later, the little ones hatch into larvae and "basically eat the berry from the inside-out."
The three-to-nine-week life cycle of the SWD turns an infestation from bad to worse, with generations of flies individually laying 300 eggs, sowing devastation into Michigan's strawberry, cherry, blackberry and blueberry fields.
If a buyer finds a single SWD in a shipment, it won't sell the fruit because of a zero-tolerance policy.
"As soon as we see a blue blueberry we immediately start preventing and taking care of and hopefully getting rid of that fly," said DeHaan.
Crossroads Blueberry Farm— nestled a few miles inland from the shore of Lake Michigan— spends an extra $200 per acre yearly, spraying SWD-specific insecticides. It also combs its rows for damaged berries and hangs sugary-sweet traps from trees.
When the East Asian fly first broke onto the Michigan fruit scene in 2010, growers scrambled to find an Achilles Heel, experimenting with reentry and pre-harvest intervals for insecticide application.
DeHaan says Crossroads struck a balance to the point where it now sidelines the SWD to five-to-ten-percent of its crop yield: "We've learned."
But when prevention is successful, it's also expensive.
"If we could eliminate that and make our summers more fun as far as not having to spray for this, that would make it better for us for sure."
The entomologists at Michigan State University think they found a solution— the Samba Wasp.
"We've always been trying to find a more biological approach and that's where this new wasp is so important," said Rufus Isaacs, professor of entomology at the university.
Dwarfed by a ripe blueberry, the small wasp doesn't sting humans but rather lays eggs in SWD larvae, killing the invasive species.
The university chose the wasp— approved last year for release by the USDA— because of its selective behaviors toward the SWD.
"I think the risk has been very carefully evaluated and is absolutely minimal," Isaacs said.
This summer, Isaacs is monitoring wasp populations released last year on a handful of farms across the mitten. But if they're to deliver thousands to Michigan's hundreds of farms, they'll need deeper pockets.
Last summer, Sen. Gary Peters (D-Mich.) introduced the Spotted Wing Abatement Trust Act (SWAT Act) to stomp out the fly. The bill would establish a federal fund for research and pest control, supplying the USDA with $6.5 million every year for the next five years.
"If we can find natural ways to control a pest, we should always be focused on that," Sen. Peters said.
This spring, the senator reintroduced the legislation, packaging it in the 2023 Farm Bill, which faces a September deadline for passage.
"There are hundreds of blueberry farms, hundreds of cherry farms around the state that would love to have this tool in their toolbox," Isaacs said.
In West Michigan, blueberry farms were host last year to six Samba Wasp release sites. If the insect survived a snowy winter, its perseverance could signal savings for Crossroads.
"We don't want to spray either because it's time consuming, it's expensive," DeHaan said. "If there's something that can be used biologically to take care of this pest it's a win for everybody."
