When the Fruit Flies Came: A Season of Zucchini, Squash, and Cucumber Troubles
I had big hopes for my garden, growing larger quantities of zucchini, squash, and cucumbers, with the goal of preserving part of the harvest.
Planting Squash: Seed Trays or Direct Sowing
I started everything from seed planted in trays, not direct sown. I transplanted them while still small, as temperatures began to rise. I avoid direct sowing these days because the seeds tend to get picked off by birds and other hungry critters before they even sprout.
But I made sure the trays were not too small to ensure that the root would not get disturbed during transplanting. Even though cucurbits prefer to be direct sown, with some care transplanting can do just fine. Especially if you want to get a head start.
Here is what I planted this season:
- Green zucchini
- Patty pan squash (Bennings Green Tint)
- Pickling cucumber
- Marketmore salad cucumber
Other members of the cucurbit family – like pumpkin, luffa, and melons – didn’t do as but for different reasons. Had they matured enough, I am sure they would have also been affected.
The seedlings took off beautifully after being transplanted. For a few weeks, everything looked perfect. The plants flowered and started producing. I hand-pollinated the zucchini and squash when I could to increase yields. The cucumbers climbed their trellis nicely, and even the squash responded well to being staked. I had tied their stems up and removed lower leaves to prevent disease from the soil, something I will absolutely do again and highly recommend.
Then the Trouble with the Pumpkin / Cucurbit Fruit Fly Began
After the initial excitement, some delicious meals, and a few jars of pickles, the trouble began.
It was not the squash vine borer which can be a common problem. These moths lay their eggs on the stalk, develop inside the stem and feed on it. The damage to the plant is significant and can quickly kill it.
My cucurbits were all looking healthy and continuing to produce. But when looking more closely at the fruit, I noticed tiny sting marks with light browning around them. When I cut the affected fruit open, I found small maggots inside. The fruit can look deformed, starts to soften and rot quickly. The culprit is a cucurbit fruit fly (or pumpkin fly) which stings the fruit and lays its eggs. The emerging larvae look like small maggots. The fly has yellow markings resembling a wasp. This is a helpful resource to learn more about it
I hadn’t taken any preventative steps. No traps, no netting, no covering the soil. I just didn’t think I needed to. And to be honest, I didn’t know how quickly it could happen.
I tried to save what I could, but most of the harvest was lost. The plants still looked healthy, but the fruit were all stung.
Despite the disappointment, I still managed to get a few good harvests early on. Luckily I had planted early in the season when the fly is not as active yet. But in peak summer the plants did not have a chance. It wasn’t a total loss, I will be ready for next season.
How to Manage Cucurbit Fruit Fly Damage
- Plant as early as possible before the pest pressure gets high
- Set up Biolure and trap system by Livingseeds early on, before flowering
- Consider using mesh to protect fruit (though it means more hand pollination)
- And keep a closer eye on the early signs
Gardening isn’t just about the harvest. It’s also about the learning — even when things go sideways. And this season taught me a lot.
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