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What are Cucumber Beetles?

Anna Harrison
Anna Harrison

There are two types of cucumber beetle that belong to the Diabrotica family. The striped or spotted cucumber beetle varieties are both considered harmful garden pests, and can do extensive damage to not only cucumber plants, but to many other vegetables and ornamental plants. They are yellow-green or orange in color with either black stripes or spots and are quite small — just 1/4 inch (6.4 mm) long. Cucumber beetles harm vegetation in the larvae stage by eating small, tender young plants as they emerge from the soil, and by burrowing into the ground and feeding on the roots. Adults eat the flowers, leaves, and stems of larger plants.

Although cucumbers are their preferred food, there are well over 200 different plants that these pests will eat. Other cucurbits such as squash and melons are especially prone to damage from these beetles and their larvae. Plants that have yellow flowers, including bean and tomato plants, are the most attractive to them. Eggplant, asparagus, cabbage, and peas are frequently visited by these bugs as well.

Ladybugs eat cucumber beetle eggs.
Ladybugs eat cucumber beetle eggs.

The striped cucumber beetle often over winters in northern climates and begins attacking plants in early spring when the temperature reaches about 65° Fahrenheit (18° Celsius). The spotted cucumber beetle is found year round in southern areas, but migrates north in early summer to do its damage. In the south, it also appears several weeks after the striped variety. Cucumber beetles often spend winters in corn fields and compost piles, where they can spread the bacterial wilt and mosaic diseases that live through cold winters in their intestines. These diseases then spread to the next season's crops.

Cucumber beetles often attack asparagus.
Cucumber beetles often attack asparagus.

Cucumber beetles can be controlled by growing plants that repel them, including radishes, calendula, marigolds, and catnip. These may help to keep the cucumber beetles from damaging other nearby plants. These beetles also have many natural predators such as nematodes, soldier beetles, and braconid wasps. Ladybugs are also beneficial because they eat the beetle eggs. These insects can purchased and introduced to an area with cucumber beetle infestations.

Peas are often attacked by cucumber beetles.
Peas are often attacked by cucumber beetles.

There are many other ways to discourage cucumber beetles without using harmful chemicals. Some gardeners and farmers spread onions skins or wood ashes on the ground near their plants. A spray containing hot peppers and garlic may also help to deter the beetles. It may be necessary to use chemicals such as rotenone or pyrethrum for severe infestations, although they cannot be used on sensitive cucurbit plants.

Frequently Asked Questions

What are cucumber beetles and why are they a problem for plants?

A cucumber.
A cucumber.

Cucumber beetles are small, yellowish insects with either black stripes or spots. They pose a significant threat to cucurbit crops (like cucumbers, melons, and squash) by feeding on their leaves, flowers, and fruit. Moreover, they can transmit bacterial wilt and squash mosaic virus, which can devastate crops and lead to significant agricultural losses.

How can you identify a cucumber beetle infestation in your garden?

Growing marigolds may help to keep cucumber beetles from damaging other nearby plants.
Growing marigolds may help to keep cucumber beetles from damaging other nearby plants.

An infestation can be identified by the presence of adult beetles, which are about 1/4 inch long, and their distinctive markings. Additionally, look for chewed leaves and flowers, and stunted or wilted plants, which may indicate the spread of bacterial wilt. Larvae, which feed on roots, can also cause yellowing and wilting of plants.

What natural predators help control cucumber beetle populations?

Natural predators of cucumber beetles include birds, spiders, and predatory insects like ground beetles, tachinid flies, and braconid wasps. These predators can help manage beetle populations by feeding on both the larvae and adults. Encouraging these beneficial species in your garden can be an effective part of integrated pest management strategies.

Are there any effective organic methods to control cucumber beetles?

Yes, organic methods include using floating row covers to protect plants, especially during seedling stages. Additionally, applying kaolin clay can deter beetles, and botanical insecticides like neem oil may reduce beetle numbers. Introducing beneficial nematodes to the soil can target larvae, and crop rotation helps prevent the buildup of beetle populations.

Can cucumber beetles affect home gardens or are they only a concern for commercial agriculture?

Cucumber beetles are a concern for both home gardens and commercial agriculture. In home gardens, they can cause significant damage to a small number of plants, potentially ruining the harvest. Vigilance and early intervention are key to preventing and mitigating damage in both settings.

What is the lifecycle of a cucumber beetle and how does it affect control methods?

The lifecycle of a cucumber beetle starts with eggs laid near host plants. Larvae emerge and feed on roots, while adults consume leaves and flowers. Understanding this cycle is crucial for timing control methods effectively. For instance, applying treatments when adults are active and before they lay eggs can reduce future populations.

Discussion Comments

honeybees

Has anybody had good results using an organic spray for spotted cucumber beetle control?

I have been trying to grow an organic garden, and sometimes have a hard time finding organic solutions that work very well.

Finding an organic spray would be my first choice, but I also want something that is going to get the job done.

Sometimes I have almost waited too long to see if something is going to work or not. I don't want the chemicals in my garden, but also want a good crop of vegetables.

bagley79

I call these pests squash beetles, but think they are the same thing as cucumber beetles. They can ruin a great crop of squash in a few weeks.

What is so frustrating about these squash bugs is they ruin many different parts of the plant. They can destroy the flowers, and also feed on the roots.

One year I almost lost a large part of my squash and melons because they spread a wilt disease that affected almost all of my plants.

Living in the country and being surrounded by corn fields probably doesn't help my situation any. I don't leave piles of leaves or mulch around, as this is a perfect breeding ground for these pests.

golf07

@myharley - I have been gardening for many years, and fighting the bugs and pests is part of it. Don't give up, as there is great reward in gardening and growing some of your own food.

There are several ways to handle cucumber beetle control, but what works best for me is spraying them. I have some local garden centers, who are helpful at recommending what works for something like this.

There are also several places online where you can order sprays to kill cucumber pests.

I have tried picking them off when I see them. Usually I will see them in the early morning, but this is time consuming and not effective in getting rid of all of them. I can't keep up with these guys.

Another thing to remember, is they can have up to three generations of these pests every summer. This is something you need to stay on top of all season long, or they will take over in a hurry.

myharley

I am pretty new at gardening, and after reading this article, realize that cucumber bugs must have been part of my problem this year.

I planted some tomatoes, cucumbers and beans, and was looking forward to growing some of my own vegetables. As the summer went on, my garden wasn't producing nearly as well as I thought it would.

It looked like a had several cucumbers and tomatoes on the vine, but didn't end up getting very much produce.

I am wondering how to get rid of cucumber beetles? I am not ready to give up on gardening, but want to find a way to control pests like these.

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    • Ladybugs eat cucumber beetle eggs.
      Ladybugs eat cucumber beetle eggs.
    • Cucumber beetles often attack asparagus.
      By: Tatiana Belova
      Cucumber beetles often attack asparagus.
    • Peas are often attacked by cucumber beetles.
      By: sevenk
      Peas are often attacked by cucumber beetles.
    • A cucumber.
      By: Kenishirotie
      A cucumber.
    • Growing marigolds may help to keep cucumber beetles from damaging other nearby plants.
      By: Dionisvera
      Growing marigolds may help to keep cucumber beetles from damaging other nearby plants.