Last Updated on April 12, 2024 by Real Men Sow
Cucumber beetles can cause damage at any stage of plant life. They can cause damage to your plants by feeding and also transmit bacterial wilt. You’ll notice one morning when you walk into your garden that your gourd crops or seedlings seem to be in a bad shape all of a sudden. What can you do?
First of all, you need to find the problem. Cucumber beetles are most likely the culprit. Although it’s not easy to completely stop cucumber beetles from infesting your garden, you can take preventative steps and implement control measures to keep them at bay.
What does a cucumber beetle look like?
There are six types of cucumber beetles found in the United States. However, only two of them are the most common to damage your crops, the Spotted Cucumber Beetle and the Striped Cucumber Beetle. These beetles have yellowish wings and measure approximately 1/5” long and 1/10″ wide.
Identifying a Cucumber Beetle
There are six types of cucumber beetle found in the United States. However, most infestations will occur from one of these two species. Here are some tips to help you identify adult cucumber beetles.
Eggs
- They are laid in groups in the soil near the base of the host plants
- Yellowish orange in color
Larva
- Known as the We
- Off-white in color
- stern Corn Rootworm
- About 3/8 inches long
Adult
- About 1/5 inches long by 1/10 inch wide
- Three longwise black stripes from head to tip with yellow wings
- Has antennae and the head is black.
- The area behind the head is orange-yellow prothorax
What can these cucumber beetles do?
Cucumber beetles can cause severe damage to your cucurbits. They eat from any part of the plant. The mature beetles eat the leaves of both seedlings as well as mature plants. After they hatch, the larvae of the cucumber beetle feed on underground roots and stems.
A minor infestation can be controlled and most mature plants will recover. However, a major infestation or one that infests small seedlings may cause severe damage and won’t be salvageable.
Erwinia Traceiphila bacteria
Cucumber bugs, especially striped cucumber beetles, can be carriers of Erwinia Traceiphila bacteria. This causes bacterial wilt in their stomachs and spreads through their feces to their mouthparts when they eat a leaf.
Plants infected by bacterial wilt can begin to wilt and the leaves will turn yellow and die eventually. Once the disease has spread quickly, the whole plant could die within days. This disease causes wilting by infecting the plant’s vascular system. There is no way to save a plant infected by bacterial wilt and should be destroyed and removed.
Cucurbits are affected by bacterial wilt in different ways. The most susceptible to bacterial wilt are cucumbers and muskmelon. Squash, pumpkins, and watermelons are usually quite tolerant to bacterial wilt or even resistant.
Tip: Wilting in cucumbers and squash is not caused by bacteria. Wilting can also be caused by squash bugs, squash vine borers, dehydration, and cucumber mosaic virus. Before diagnosing, be sure to check for any signs that indicate a disease or insect.
Are cucumber beetles dangerous?
Cucumber beetles can be controlled in small numbers, as well as on mature plants. Cucumber beetles can cause severe damage to plants, whether they are in large numbers or as seedlings. Remember that even small numbers of cucumber beetles can spread bacteria wilt, so it is best to get rid of the problem as soon as possible.
Are there natural enemies to cucumber beetles?
Although it is not an easy fix, increasing the natural predators for cucumber beetles can help to prevent future infestations. These beneficial insects are natural enemies to cucumber beetles:
- Ladybugs
- Braconid wasps
- Beneficial nematodes
- Soldier beetles
- Green lacewing
- Assassin bugs
These beneficial insects can be attracted by you planting companion crops, or nearby cover crops such as sweet clover, which has been shown to increase cantaloupe crop yields by decreasing the cucumber beetle population. Cucumber beetles can also be controlled by plants that increase beneficial insect populations.
Drawing away cucumber beetles
To repel cucumber beetles, companion planting is another option. Interplanting high-scent flowers and herbs with cucumber beetles will confuse them so they don’t find your cucurbits. You have many options for fragrant plants, including marigold, sage, and catnip.
A trap crop is another way to plant cucumber beetles. A trap crop is a type of plant that is used in the garden as a sacrificial lamb. Two weeks before your main crop, plant a crop that is especially tasty to cucumber beetles around the garden’s perimeter. You can leave the rest alone as the beetles will only be attracted to this plant. The trap crop can then destroy these cucumber beetles by either mechanical (flaming, vacuuming using a shop vacuum, or handpicking), or biological (organic insecticides).
Preventing Cucumber Beetles
Prevention, also known as cultural control, is the best way to ensure that cucumber beetles don’t decimate your squash, melons, and cucumbers. Here is our prevention plan.
- Clean up any garden litter or leaf litter left over from the previous year. The Cucumber beetles spend the winter in garden litter and mulch.
- Rotate your crops. If possible, do not grow cucurbits in succession.
- Try to plant crops that attract beneficial insects. To attract cucumber beetles’ natural enemies, plant crops such as cowpeas, milkweed, clover, and other pollinator-friendly vegetables in your garden.
- You can interplant cucumber beetle-resistant plants with your cucurbits. The beetles can be disoriented and confused by heavy companion planting of aromatic herbs and flowers such as marigolds, sage, and tansy.
- You can try a trap crop. Two weeks before planting your other cucurbits, plant a cucumber plant around your garden’s perimeter. You can destroy the cucumber beetles by using biological or mechanical control, as they will flock to this plant from late April through early June.
- Row covers are a good option. Row covers made of insect netting can be used to prevent new cucumber beetles from infesting, but they are not effective at stopping an infestation that occurs after eggs hatch from overwintered honey beetles. To allow pollinators to access your plants’ flowers, you must also remember to take off your row covers.
Getting rid of Cucumber Beetle Infestation
Let’s say that you were unable to implement a preventive strategy or that you tried but failed. What should you do?
Tip: Because many insects, pests, and cultural issues can cause wilting of cucumbers, be sure to identify any adult beetles before you treat them.
Mechanical/Physical Control
- Try to interrupt the cucumber beetle’s life cycle. Although tedious, it is possible with some mechanical control methods.
- To reduce small infestations, you can handpick the beetles. Then, rinse them with soapy water and place them in a bucket. You should also smash any eggs or larvae you find.
- Shop vacuums or leaf vacuums (with a bag attached), can be used to remove heavy infestations. This is especially useful for managing pests on trap crops.
- A weed torch is a great way to get rid of all larvae and eggs. However, this will also kill your cucurbit plants. Flaming can be used to rehabilitate a garden bed that was subject to a severe infestation and make it suitable when planting in the future.
Biological/Chemical Control
It is best to use a combination of biological, cultural, as well as mechanical methods to control heavy cucumber beetle infestations. This will help protect pollinators. When you only rely on chemicals, it can often prove ineffective. It increases the likelihood of beetles that are resistant to chemicals and is bad for our beloved honeybees.
Neem Oil is a plant-based insecticide that stops cucumber beetles from eating. They eventually starve to death. Neem oil can be moderately toxic for bees and other pollinators. It should not be used during the late evening, night, or early morning when flowers aren’t in bloom, and it is important that you don’t apply it.
Pyrethrum is an organic pesticide derived from the Pyrethrum daisy. It is loaded with toxic chemicals called pyrethrins, which are harmful to insects. Pyrethrum is toxic to nearly all insects. It can also be deadly for beneficial insects, pollinators, and other insects. Therefore, it should only be used when bees are not active.
Kaolin Clay leaves behind a film that cucumber beetles find unattractive for egg-laying and feeding. Sprinkle it on the affected plant leaves after you have identified beetle damage. You can also mix it with water, and spray it onto the foliage. The spray will dry into a film. Be sure to apply it when the bees or other pollinators aren’t active.
Spinosad, a natural substance that is made from bacteria, can be toxic to insects. This bacteria causes paralysis in the insects and ultimately death. Spinosad can be moderately toxic for earthworms and very toxic to bees. However, it is less toxic after it has dried.
Tip: When managing cucumber beetles, we recommend that you use both prevention/cultural control as well as mechanical controls. Chemical control should only be used as a last resort to protect beneficial insects and pollinators.
Prevention is key to success in stopping cucumber beetles from infesting your home garden. If you follow our plan you will have a bumper crop this year of squash, melons, and cucumbers.
