There are two types of cucumber beetles: the striped cucumber beetle (Acalymma vittatum) and the spotted cucumber beetle (Diabrotica undecimpunctata howardi).

Both of these beetles primarily eat the leaves, flowers, and fruits of cucurbits, which include cucumbers, squash, pumpkins, and melons. They can also feed on other plants like beans, corn, peanuts, and potatoes.

Here are some differences between the striped and spotted cucumber beetles:

  • Spotted cucumber beetles feed on over 200 different plants, while striped cucumber beetles prefer cucurbits and rarely eat other plants. Striped cucumber beetles lay their eggs at the base of cucurbit plants, and their larvae feed on the roots of these plants.
  • Spotted cucumber beetles, on the other hand, lay their eggs primarily on corn and other grasses. The larvae of spotted cucumber beetles don’t cause damage to cucurbit crops. After hatching, the larvae feed on root tissue for several weeks.
  • The damage caused by the larvae may not be visible by looking at the aboveground foliage. However, if you try to pull up a plant and it comes out easily due to eaten roots, then you’ll know that there is damage. The larvae pupate in the soil for about a week and then emerge as adult beetles.
  • Striped cucumber beetles are yellowish-green or orangeish-green with three black stripes on their backs. Spotted cucumber beetles are also yellowish-green or orangeish-green but have 12 black spots on their backs.
  • Both beetles are about 1/4 inch in length.

Cucumber beetles are a significant concern as they can cause significant losses and can also spread diseases.

The adult beetles mainly feed on foliage, pollen, and flowers. However, if they feed on melon rinds late in the season, it can reduce the quality of the produce.

Life cycle

Cucumber beetles spend the winter as adults in protected areas such as plant debris, fence rows, or wood lots. They become active when temperatures start to rise.
The adults feed on plants and the females lay eggs in cracks in the soil near the base of cucurbits. The eggs hatch in a few days, and the larvae feed on the roots and underground parts of the stem. Pupation occurs in the soil, and the next generation of beetles emerges.
It takes about 40 to 60 days for these beetles to go from an egg to an adult.

Damage

Cucumber beetles eat the leaves, flowers, and fruit of the host plants. Their larvae feed on the roots and underground parts of the stems. If the beetle population is high, they can also feed on the stems of the plants.

These beetles damage cucurbit crops in three main ways:

1. Their feeding directly affects plant growth, and when they eat flowers, it reduces fruit production.
2. Cucumber beetles can transmit diseases such as mosaics and bacterial wilt (Erwinia tracheiphila).
3. The adult beetles can scar the fruit, making it less marketable.
Young cucurbit plants are particularly vulnerable to stunting and bacterial wilt disease, while damage to older plants mainly comes from fruit scarring.

Management strategies

Chemical method

Several insecticides can be used to control cucumber beetles, such as KINGCODE ELITE 50EC, LEXUS 247SC, SINOPHATE 750SP, EPITOME ELITE 500SP, PRESENTO 200SP, PROFILE 440EC, and PENTAGON 50EC. The recommended application rates are provided.

Non-chemical control methods

  • Yellow sticky traps can be used to catch cucumber beetles.
  • Beetles can be knocked to the ground and collected using a piece of cardboard placed under the plant. Alternatively, a handheld vacuum can be used to remove the beetles.
  • Covering seedlings with row covers can help protect them, but the covers should be removed during flowering to allow for pollination.
  • Planting resistant varieties whenever possible can be effective.
  • Beneficial insects like ladybugs, green lacewing, and spined soldier bugs, which feed on pest eggs, can be introduced.
  • Beneficial nematodes can be used to control immature stages of cucumber beetles in the soil.
  • Removing garden debris after harvest reduces overwintering sites for the beetles.
  • Rotating with non-host crops can help break the pest’s life cycle.
  • Proper weed control is important as weeds can harbor pests.
  • Planting resistant or tolerant varieties is another effective strategy.

Note:

When using any insecticide, it’s recommended to mix it with INTEGRA, a product that improves the efficacy of the insecticide. To prevent resistance buildup, it’s advisable to alternate between different insecticides throughout the crop season. Timely control of the beetles is crucial.

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