From The Farm: Experimenting With Beneficial Bugs

Dec 1, 2016

A blueberry bush at Pleasant Hill Farm
Credit Joan Donaldson

Joan Donaldson and her husband own Pleasant Hill Farm in Fennville. She writes about life as an organic farmer. 

Over the years that my husband, John and I have farmed organic fruit, we’ve experimented with introducing various beneficial insects to our crops. Boxes with screens have arrived where thousands of lady bugs’ legs crawled across the wire mesh. 


We drove to various places in our blueberry fields and released a red cloud of them that hovered and then dispersed between the bushes. Then in my garden, I shook out the few reluctant lady bugs who refused to leave their shelter, so that they could eat harmful insects on my vegetable plants.

Though it looks like sandpaper, these strips contain the tiny eggs of a wasp that fights cranberry parasites.
Credit Joan Donaldson

In the same way, we set free praying mantis in order that they could eat pests. For the past couple of springs, I’ve cut apart thousands of little black strips of paper sprinkled with what looks like pepper - instead they’re the eggs of a small wasp that is a parasite for cranberry fruit flies.

While crickets chirped, John and I tramped through our 40 acres of bushes, down every fourth row, and on every tenth bush, we hung one of the paper strips. When the larvae hatched, the beneficial wasp laid their eggs in the fruit fly’s larvae and eliminated the need to spray even an organic pesticide such as pyrethrum.

Sometimes our organic helpers live in the dirt. I once heard nematodes - microscopic worm-like creatures - were to blame for twisting my carrots into tangled shapes or harming the roots of peach trees, eventually killing them. Nematodes were bad; a gardener’s enemy.

But then, about 20 years ago, John began to talk about beneficial nematodes that might help protect our blueberry bushes. He spent time talking with an entomologist at Michigan State University who shared a deep interest in nematodes. Dr. George Bird found a small amount of funding, and one day our mail carrier delivered a tiny box that John rushed into our refrigerator.

“What’s in it?” I peeked at the nest of moist, shredded newspaper enclosed in a plastic bag. “Why must it be kept cold?”

“Nematodes that Dr. Bird and I will spray in the bog, and see if they will eat the larvae of blueberry flies. But we need a wet, rainy morning for the job,” John said. 

A few days later, the weather forecast predicted the necessary climate conditions. Just before dawn as the skies sprinkled rain, Dr. Bird arrived, and the two men rumbled down to the bog with our spray rig and squirted under the blueberry bushes a mixture of water and nematodes. At various times in the next couple of years, John tested the soil for the nematodes, but found little activity. 

Sometimes we discover unknown insects are working for our benefit beneath our feet

Like other scientific experiments gone awry, he concluded that this critter was not a solution to eradicating our pests. John forgot about the nematodes and focused his energy on making compost tea and finding other ways to grow the healthiest blueberry bushes so that the plants could resist funguses and insects.

Last year, the head of the organic department at MSU was awarded a large grant to work on finding an organic solution to stamping out the latest invasive insect, spotted-wing drosophila, or as we say, SWD. Our farm is participating in the research and during the summer, three teams of graduate students and post-doctorate students drove out each week to check their traps and gather data.

One of the MSU researchers also dug soil samples from various locations so that she could examine the microbes and other life thriving in them. She explained that normally, the soil from a woodlot contains the largest amount of beneficial critters, but on our farm, the most nematodes thrived where our bushes grew. 

Over the past 20 years, the nematodes that John and Dr. Bird had released had slowly multiplied. It’s too early to know if they are one of the organic solutions in our battle to defeat SWD, but the researcher is hopeful and so are we.

Sometimes we discover unknown insects are working for our benefit beneath our feet.