Cucumber Beetles

by Daisy on 07/08/2013

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Year before last, I had so many cucumbers I didn’t know what to do with them.   I collected baskets and baskets and made dozens of jars of relish, pickles, and jelly.  Just kidding, I didn’t make cucumber jelly.

But I was tempted.

Then last year, I blithely planted cucumbers again without a worry in the world, and sat back and waited for the deluge of cucurbits.

I noticed these little yellow and black striped beetles, but I didn’t notice any damage to the vines.  They didn’t seem to be eating much, so I waved it off.  The vines were growing and making little cukes, so I figured it was business as usual.

Then . . . the leaves started to yellow, the plants began to flag.  Production was way off.  The vines began to wilt and die.  There were TONS of those little striped beetles I had ignored.  I went into research mode, and whadya know:  I had bacterial wilt disease (Erwinia tracheiphila), or rather, my cucumber plants had bacterial wilt disease.  A disease transmitted by the piercing-sucking mischief of little yellow and black striped beetles, which have a name, by the way: Striped Cucumber Beetles.

There are striped cucumber beetles and spotted cucumber beetles.  There are differences between the two.

Striped Cucumber Beetle

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  • Strong preference for cucurbits such as cucumbers, squash, and melons
  • Lays eggs at the base of the plants and the larvae feed on the roots of the cucumber plant

Spotted Cucumber Beetle

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  • Feeds on over 200 different species of plant, not just cucurbits
  • Lays eggs on grasses and does not damage cucurbit roots
  • More often found further south than the striped cucumber beetle

They can damage leaves and blossoms and the fruit itself, but to me the most significant threat is bacterial wilt disease.  The damage to the cucumbers themselves was minimal, but killing the whole plant is where it got serious for me.

This year, I planted cucumbers again, in spite of the threat.  This time, I’m taking the SCB threat much more seriously.  I’m doing a few things that are recommended for the organic control of this pest:

  • straw mulch–slows beetle movement, provides a haven for spiders and other beneficials, & feeds decomposers that act as food for the beneficials
  • hand picking–ever day I set a quota and try to squish as many as I can
  • succession planting–I’ve planted three separate crops at different times so if one crop fails maybe I’ll get a second chance
  • growing in lots of organic matter–thought to boost the plant’s internal defenses
  • organic fertilization regime–homemade compost/comfrey tea–strong plants have better defenses

I tried using yellow cups coated with Tanglefoot and baited with clove oil but they failed to catch a single beetle.  I contemplated using a vacuum, but the bother and the noise and the likelihood I would catch (and certainly annoy the stew out of) beneficials has stopped me from trying that.

There are, of course, organic-approved sprays, etc., but those still carry with them some danger of harming beneficials.  Over time, organic conditions, what Eliot Coleman calls “Deep Organic,” lead to a balance of beneficials and pests and such healthy soil that pest and disease issues subside.  Every time I bring out the sprays and dusts, however organic-approved, I get the feeling I’m setting back a natural balance a few steps.

Other controls that are suggested include row covers until blooms appear, trap crops on the perimeter of the garden, and planting resistant varieties.

At the present, things are looking much better than last year, and time will tell whether or not I need those second crops of cukes and whether or not they make it.

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A note on hand picking cucumber beetles:  They are very shy and sensitive to movement.  You have to be very fast and think like a predator.  When disturbed they usually let go of their footing and drop straight down.  Either be too fast and stealthy for them or anticipate the drop and have a hand underneath to catch them.  They also simply fly off.  The best time I have found to catch them is early in the morning, especially after a rain, when I tend to find them in pairs (two for one squish).



{ 15 comments… read them below or add one }

Hannah July 8, 2013 at 4:56 pm

I use a rectangular plastic dishpan with 1/2 cup of soapy water, and knock the bugs off into that. Once they’re wet, they don’t fly away.

Phyllis July 9, 2013 at 6:04 am

I have used tweezers when they are in the flowers. Odd, but it works!

Kitchen Witch Skyfae July 10, 2013 at 3:21 am

Good to know for next year, I didn’t get my planting box made for this year and everything I’ve tried to grow from seed to potted plant dies on transplant. 🙁

Laurie July 10, 2013 at 5:27 am

Ha! I recently noticed these little beasts. I think we caught them in time to control, but I’m headed outside to check. I appreciate your posts. I pulled two of those worms off my tomato plants yesterday. Unfortunately, the Japanese beetles have destroyed my Rose bush. We are learning as we go. 🙂

Cynthia C July 10, 2013 at 11:33 am

We have those spotted little beasts! They’re terrible. They really ruined my beans last year. This year we had a new little bug – they were a little smaller than the spotted cucumber beetle, but brown – and they chowed on my bush beans. We have Stink bugs in the gigantic 14 feet teepee of pole beans.

We recently released praying mantis, which has helped some. Last year we gave the kids little jars with a little rubbing alcohol in them and gave them 5 cents for each bug – it funded their ice cream habit 🙂

Sarah July 10, 2013 at 11:40 am

Ya know…I’m so new to gardening, I think we may have those. Our cucumber plant is looking pretty sad, but still producing a little bit. Silly me, when I saw one that looked like the spotted variety I thought it was a different color ladybug. I’ll have to look more closely.

Sarah July 10, 2013 at 3:25 pm

I totally have these, and resorted to spraying early in the spring, I was so alarmed by how many I have. Then, my plants looked better, so I ignored them. Now, I’ve got a couple of plants that are looking yellow, so back out I go, but this time, I’m going to just squish. I hope I didn’t wait too long.

Carey July 10, 2013 at 11:01 pm

Last year, we had them in droves! By chance we were outside one evening with the outside light on. We usually keep it off so we won’t attract bugs. We attracted bugs all right…hundreds of the cuke beetles. My husband ran in to the house, grabbed the vacuum and sucked them up! And several nights in succession until finally the numbers diminished.

Daisy July 11, 2013 at 5:51 am

Carey–Really! That makes me wonder what they’re up to at night! I should check them out after dark and see.

Samantha D July 13, 2013 at 6:58 am

I just saw one of these bugs not two days after reading your post and I’m so fortunate I did because I would never have known that these guys do damage and MUST go!TY!

Angel July 22, 2013 at 1:09 pm

I never had any problem with these insects until this year. In fact, I never seen anything like them. I have grown cucumbers for years, but this year I noticed these strange bugs. They were everywhere, on me and in my house. I would see them usually near a nightlight and wonder why they were attracted to light. The bug zapper has killed many of them that now lay on my patio. They are in the cat’s water pan outside. I couldn’t take anymore of this invasion, so I used Seven on the Cucumbers and potato plants which I do not like doing, but, I had had enough. Hope it takes care of most of them. Also, I am growing melons for the first time. They may have attracted them.

Sheila May 1, 2016 at 7:50 am

I have grown English cucumbers for years and never had a problem. Last year, my plants were infested with the striped cucumber beetle. I used a spray of soap and water with no luck. Finally got some insecticide spray but, by then, my plants were damaged & my cucumber crop was sparse.
If I had these beetles last year, will they infest again even if I plant the cucumbers in a different side of the garden & would row covers keep the beetles away and protect the plants? H E L P!!

Daisy May 1, 2016 at 8:54 am

Sheila–Sorry about last year’s crop. I think if you do what you plan you will at least minimize and delay the damage and be able to get a good crop before the damage (if any) is significant. Even when I have cucumber beetles, the vines still manage to put out a lot of fruit before the plant succumbs.

Sheila May 1, 2016 at 10:09 am

Re cucumber beetles – IF I wait until the first week of June to plant, will that help to deter these cuke beetles??

Daisy May 1, 2016 at 2:35 pm

Sheila–It can help. Waiting until the last minute (just enough time left for the vines to fruit before frost) may give the beetles time to find someone else’s cucurbits to munch upon. When that is will depend on where you live, but late June/early July is about right for the US Midwest.

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