Friday, July 20, 2012

Guide to Identifying and Controlling Cucumber Beetles Organically

Not only do cucumber beetles live in Maine’s organic vegetables gardens, they thrive throughout the entire U.S. and most of Canada. These pests eat through leaves, flowers and fruits as adults and borrow their way into the base of plant stems and eat away at roots at the larval stage, often killing young plants. There are 4 ways to control cucumber beetles organically before, during and after the growing season.

Cucumber Beetle Identification

Wondering how to identify cucumber beetles? It’s pretty easy when you know what to look for. There are 2 types of cucumber beetles and here’s how to identify each.

Striped: Adult striped cucumber beetles grow to about 1/4 inch long with black heads and have 3 black stripes running down their backs that are big enough to identify. Their larvae are bigger, about 3/4 inches long with reddish brown heads and thin, white bodies. (see above picture)

Spotted: Adult spotted cucumber beetles grow to about 1/4 inch long and have 12 black spots dotting the coverings of their wings. Their larvae look the same as striped cucumber beetle larvae.

Common Plants Cucumber Beetles Attack

  • Cucumbers
  • Pumpkins
  • Melons
  • Squash
  • Corn

When They Feed and Reproduce

Spotted cucumber beetles come out from April to early June, eat for 2 weeks and lay their eggs. When the eggs hatch into larvae, the larvae feed for 2 to 6 weeks before turning into adults and starting the cycle again. Spotted beetles have been known to produce up to 4 generations a year.

Striped Cucumber Beetles come out in spring. The adults lay their eggs near the soil’s surface, particularly near corn plants when they are available. Once the eggs hatch and larvae appear, they feed for 2 to 4 weeks before turning into adults and starting the life cycle again. Striped beetles can produce up to 3 generations each year.

How to Identify Cucumber Beetle Damage

When cucumber beetles have finished feeding and have moved on to new plants or to lay their eggs, they leave behind plenty of damage letting gardeners know they’ve been there. To identify damage left by these common garden pests, look for skeletal-like leaves that have browned and turned brittle. Also look for holes that have been chewed through flowers and fruits.

Image: © Patrice Beaulieu

4 Ways to Control Cucumber Beetles Organically

1. Floating Row Covers: Protect young plants with floating row covers as soon as seedlings germinate. This will help keep cucumber beetles away organically. Watch for plants to flower and as soon as they do, roll back the floating row covers for a few hours each day to allow the plants to be pollinated.

2. Wilt/Mosaic-Resistant Varieties: When choosing varieties of plants for the garden, plant those that are known to be resistant to wilt and mosaic virus. Seed companies include which viruses and diseases plants are resistant to in the plant’s description in catalogs and on seed packets.

3. Non-Bitter Varieties: Cucumber beetles prefer non-bitter varieties of cucumbers so plant non-bitter varieties in the garden.

4. Remove Dead Plants: When the growing season has come to a close, remove all dead plants and debris from the garden. This measure helps control cucumber beetles organically because the beetles over winter under clumps of dead plants.

When it comes to insects, cucumber beetles are one of the top garden pests in Maine. In this area, July is the prime month for adult beetles to begin emerging and leaving behind a path of destruction. The good news for organic gardeners; these pests can be controlled without the use of pesticides leaving the garden chemical-free.

What’s Going on in Gibby’s Garden?

It’s mid July and cucumber beetles are out in full force in Gibby’s Garden. This weekend I noticed the leaves of my squash plants had been heavily damaged by cucumber beetles. I sprinkled my plants with ground black pepper. This method is organic and works well in conjunction with the methods listed in this post. For some reason, cucumber beetles don’t like black pepper, but hey, neither do I.

Check out Gibby’s Garden Diary to see what else is going on in Gibby’s Garden.

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Reference: Rodale Organic Gardening (2001). Basics:Pests Volume 7. Rodale Inc.

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