Cucumber beetles are a common pest that can cause significant damage to vine crops such as cucumbers, squash, pumpkins, and watermelons. These beetles can affect the roots, leaves, flowers, and fruits of these plants, and even interfere with pollination, leading to reduced fruit sets [1(https://hort.extension.wisc.edu/articles/cucumber-beetles/).
There are two main types of cucumber beetles: the striped cucumber beetle and the spotted cucumber beetle. The striped cucumber beetle has three black stripes on its wings, while the spotted cucumber beetle has 12 black spots 2. Both types have similar life cycles and feeding habits, with larvae feeding on plant roots and stems, and adults feasting on seedlings, flower petals, and leaves 3.
Managing cucumber beetles can be done through various approaches, including the use of kaolin clay, which creates a gummy coating on the beetles’ antennae, making it difficult for them to navigate. However, it’s important to note that kaolin clay will not kill cucumber beetles 4.
Cucumber Beetle Identification
Striped Cucumber Beetle
The striped cucumber beetle (Acalymma vittatum) is a common garden pest often found attacking cucurbits, such as cucumbers, melons, and squash1. These beetles are characterized by:
- Size: approximately 1/5 inch long
- Color: yellow with three distinct black stripes running down their wing covers
- Antennae: reddish-brown in color
Striped cucumber beetles can cause damage by feeding on the foliage, flowers, and fruit of host plants2. Additionally, they can transmit bacterial wilt, leading to plants wilting and dying3.
Spotted Cucumber Beetle
The spotted cucumber beetle (Diabrotica undecimpunctata howardi) is similar in size and shape to the striped cucumber beetle4. Here are some distinguishing features:
- Size: about 1/5 to 1/4 inch long
- Color: yellow with 12 black spots on their wing covers
- Antennae: also reddish-brown in color
This beetle causes damage by feeding on roots, stems, and fruits and can potentially transmit plant diseases5.
Comparison
| Feature | Striped Cucumber Beetle | Spotted Cucumber Beetle |
|---|---|---|
| Size | Approximately 1/5 inch long | 1/5 to 1/4 inch long |
| Color | Yellow with black stripes | Yellow with black spots |
| Antennae color | Reddish-brown | Reddish-brown |
| Feeding habits | Foliage, flowers, and fruit | Roots, stems, and fruit |
Life Cycle and Behavior
Egg
- Cucumber beetles lay eggs in soil or near plant stems
- Pale orange-yellow in color
- Egg-laying occurs mostly during late summer
Cucumber beetles, both striped and spotted species, lay their eggs in the soil or close to the base of plants. The eggs are pale orange-yellow and are usually laid during late summer.
Larva
- Feed on roots and stem base
- Creamy white color
- Grow up to 3/8 inches in length
The larvae, also known as rootworms, hatch from the eggs and feed on the roots and stems of plants. They are small, with a creamy white color and grow up to 3/8 inches in length.
Adult
Striped Cucumber Beetle:
- Yellowish-green color
- Three black stripes on wing covers
- About 1/5-inch long
Spotted Cucumber Beetle:
- Yellowish-green color
- 12 black spots on wing covers
- Similar size and shape as striped cucumber beetle
Comparison table:
| Striped Cucumber Beetle | Spotted Cucumber Beetle |
|---|---|
| Three black stripes | 12 black spots |
| Yellowish-green color | Yellowish-green color |
| About 1/5-inch long | Similar size and shape |
The adult beetles emerge after the larval stage and feed on plant foliage, flowers, and seedlings. There are two main types of cucumber beetles: striped and spotted. Striped cucumber beetles have three black stripes on their wing covers, while spotted cucumber beetles have 12 black spots. Both types of beetles are yellowish-green in color and about the same size.
Adult cucumber beetles overwinter in plant debris, becoming active again in the warmer months. They mate and lay eggs, completing their life cycle. The adult beetles can cause significant damage to cucurbit plants, such as cucumbers, squash, and melons, making their management crucial for maintaining healthy gardens and crops.
Damage to Cucurbits
Cucumbers
Cucumber beetles (Acalymma vittatum) cause significant damage to cucumbers by feeding on their leaves, blossoms, and stems. They also transmit bacterial wilt, a disease that leads to plant death. Common signs of damage include:
- Holes in leaves
- Yellowing or wilting leaves
- Stunted growth
Squash
Squash plants are particularly susceptible to damage from both spotted and striped cucumber beetles. A successful control method involves planting Blue Hubbard squash, which acts as a trap crop by attracting beetles, saving the main squash plants from infestation. For example:
- For a small garden with 100 cucurbit plants: plant 6-8 Blue Hubbard squash plants
- For a small farm with plastic mulch and drip irrigation: transplant 2-4 Blue Hubbard squash seedlings
Melons
Cucumber beetles prefer melons over other cucurbits. They feed on leaves, fruit, stems, and can transmit diseases like bacterial wilt and cucumber mosaic virus. The result is:
- Misshapen or discolored fruit
- Premature fruit drop
- Plant death
Pumpkins
Pumpkins are also at risk when infested with cucumber beetles. Similar to other cucurbits, the damage includes leaf feeding, wilt transmission, and reduced yield. Common symptoms on pumpkins are:
- Holes in leaves and stems
- Diseased plants
- Reduced fruit quality
Corn
While corn is not a cucurbit, it can also be damaged by cucumber beetles. The beetles feed on corn seedlings, transmit bacterial wilt, and cause problems like:
- Stunted growth
- Severely damaged leaves
- Reduced yield
| Cucurbit Type | Damage | Symptoms/Disease |
|---|---|---|
| Cucumbers | Leaf, stem, fruit | Holes in leaves, yellowing, wilting, bacterial wilt |
| Squash | Leaves, stems | Attracts beetles, managed with trap crop |
| Melons | Leaves, fruit, stems | Misshapen or discolored fruit, premature drop, diseases |
| Pumpkins | Leaf, stem, fruit | Holes, wilt, reduced quality |
| Corn | Leaf, seedlings | Stunted growth, damaged leaves, reduced yield |
Footnotes
