Sunday, July 29, 2012

The Zucchini Axis of Evil

When you grow food in a home garden, a big part of what you're doing is trying to create and manage order from the chaos of the natural world. We arrange raised beds in tidy rows, carefully select vegetable breeds that have the characteristics we desire, and water regularly when Mother Nature doesn't provide enough rain (especially this year!). But some unpleasant discoveries this week reminded us that in the end, we're not really in charge.

First, we've got these reddish colored perfect spheres on the underside of the zucchini leaves. These we are able to identify as squash bug eggs. You know how we can tell that's what they are? Because some of them had already started to hatch by time we found them, and they looked like this:

As adults, squash bugs are kind of shield-shaped insects with pointed snouts and an unfortunate appetite for squash leaves. An otherwise healthy zucchini plant can usually withstand an attack from these bugs, but you'll still want to get rid of them if you spot them. We don't like to use chemical pesticides, so we've been simply removing and squishing any eggs we find.

This is the next culprit we've seen around our zucchini, which are probably a bigger problem. These are cucumber beetles, but they're apparently open to eating zucchini and other squashes as well. Their larvae tunnel through the roots and stems, then the adults munch on leaves and flowers. That's not good, but the real trouble is that they spread bacterial wilt, a disease that can kill entire plants. Thankfully we haven't yet seen any signs of this disease but with so many beetles around, it's a concern.

The last scourge of the squash family is the squash vine borer, possibly the most terminal, and one that we worry we might have. As their name implies, these insects also tunnel through the stems of the plants, disrupting the flow of nutrients. Once these are inside the stems, there's no real way to see them, but you'll see the damage they cause. Stems will start to get wilty, and eventually the base of the plant will turn orange and porous in a material called frass.

This is almost certainly vine borer frass, which we can confirm by splitting and looking inside the stems. If the plants die, we'll try to do that. But if the borers are already in there, we're pretty much out of luck. We should have been on the lookout for adult borers (which are moths) in the early summer, and could have used traps to try to preemptively kill them off.

For now, though, it's a race against time, to harvest all the zucchini the plants can produce while they can. We also plan to pull and destroy any plants that do die off from apparent borer attacks. This might slow or stop their spread.

On the plus side, we have already harvested more than 10 pounds of zucchini, and are finding many delicious ways to use it. We've sliced and grilled it, we've made a chocolate-zucchini cake, and just today we baked a loaf of zucchini bread. We might not be able to completely control the insects that are attacking our plants, but we can take charge of enjoying its bounty while it lasts.


  1. I had the same squash bug eggs on my pumpkin plant, near my zuchs. The plant wasn't doing well, so I lopped the entire thing off and fed it to my chickens, who promptly ate the eggs and larva for me. What kind girls. I didn't know what they were at the time, but being so close to my zuchs I probably saved them. Thanks for the info.

  2. 1. The Hort Gang on IPR says the best way to get rid of squash bugs is to in fact squash them. A lot of pesticides don't work anyway.
    2. As travel coordinator for stitches, I demand that Stacia bring some zuchinni bread for snacks. I know I said bring your own snacks, but I am making an exception for this.