Garden Beetles: How to Control Harmful Garden Beetles

Beetles are flying and crawling insects in the vast Coleoptera order and have the potential to benefit or harm your vegetable garden or flower garden. Some beetles might eat enough garden pests in a day, making them nearly as effective as insecticides in eliminating infestations; other species of beetles might be destructive or even lethal to your plants, consuming them as food or spreading diseases to them.

There are several varieties of beetles that can benefit your plants, serving as pollinators or protecting your garden from potentially harmful species of bugs. Here are a handful of helpful critters that can provide biological control of bad bugs.

1. 1. Fireflies: Sometimes called lighting bugs, these creatures are actually beetles, not flies. As larvae, fireflies feed on other insects, snails, and worms. Adult fireflies typically feed on nectar and do not harm plants.
2. 2. Ladybugs: Also called lady beetles or ladybird beetles, ladybugs are beneficial insects. An iconic-looking red beetle with black spots, a ladybug will feed on harmful garden insects like aphids, spider mites, mealybugs, caterpillars, thrips, and scales. If you prefer all-natural pest control (instead of an insecticide), consider adding ladybugs and green lacewing larvae, another beneficial insect, to your vegetable garden. Together, the ladybugs and green lacewings are capable of consuming a large number of aphids, whiteflies, and leafhoppers.
3. 3. Ground beetles: These good bugs are big eaters. Ground beetles are a form of natural pest control, as they eat mites, snails, slugs, earwigs, cutworms, aphids, hornworms, and other potentially harmful insects.
4. 4. Rove beetles: Long and thin, these beetles resemble earwigs. But unlike earwigs, rove beetles can be beneficial bugs. This good bug will consume the eggs and larvae of harmful insects like aphids, grubs, mites, and mealybugs.
5. 5. Soldier beetles: Often referred to as soldier bugs, these beetles live on plants and eat harmful insects. Their larvae can also be beneficial in the garden, as they eat the eggs of harmful pests.

Many beetle varieties feed on plant material, including a plant’s leaves and stems, which can ultimately kill a plant. Other beetle varieties are harmful because they carry bacteria that can infect plants. For any type of pest, it's important to kill a bad bug before it can lay eggs and cause a larger infestation. Here are a few types of potentially harmful garden beetles.

1. 1. Cucumber beetles: These insect pests are extremely harmful in a vegetable garden. If you see large numbers of cucumber beetles in your garden, act immediately. The cucumber beetle can destroy your garden in two ways: by feeding on or infecting your plant. The larvae feed on roots, and the adults eat the stems, stalks, and blossoms of flowering plants, such as cucumber squash, melons, and gourds. If they don’t destroy your garden by eating the plants, they also carry bacteria that can cause a condition called bacteria wilt. Once the beetle infects it, the plant will die.
2. 2. Flea beetles: These beetles eat plant materials like leaves, but they are more harmful because they carry viral and bacterial diseases that destroy plants.
3. 3. Japanese beetles: Capable of eating plant tissue quickly, Japanese beetles can kill a plant in a few days. A tell-tale sign of a Japanese beetle infestation is a plant with skeleton-looking leaves (only the veins remain).
4. 4. Leaf beetles: There are several thousand species of leaf beetles, and each one feeds on a different type of plant. For example, there are potato beetles, elm leaf beetles, bean leaf beetles, willow leaf beetles, and tens of thousands more. What they all have in common is that they destroy the plant by eating its leaves.

There are several methods that can help rid your garden of a harmful beetle infestation. Here are pest management strategies for the most common beetle adults and their larvae:

• Beneficial nematodes: These microscopic roundworms are helpful at ridding your garden of a number of pest insects, such as cutworms, earwigs, and beetles. They target critters that live in the soil, like Japanese beetles, weevils, cucumber beetles, and flea beetles. Beneficial nematodes will not affect plant roots or harm beneficial garden insects like honey bees or earthworms.
• Milky spore: This pest control powder is actually a bacterium that targets Japanese beetle grubs. Milky spore is moderately effective and will kill only Japanese beetles, not any other types of beetle infestations.
• Neem oil: A natural pesticide, neem oil comes from extracted oil from the neem plant. It’s safe for plants, and you can spray the oil directly onto leaves. The neem oil kills or repels harmful insects, including beetles, aphids, snails, mealybugs, maggots, cabbage moths, cockroaches, whiteflies, and termites.
• Insecticidal soap: Less toxic than traditional insecticides, insecticidal soaps can help control beetle infestations. Follow the product instructions to measure and mix the soap with water to create a bucket of soapy water. Fill a spray bottle with the mixture and then spray it on plants, or apply the soapy mixture directly to the leaves. After washing the leaves, you can remove the beetles by handpicking them off the leaves. Remember to wear gloves while working with this soap and when handling the beetles.
• Pheromone traps: These beetle traps work by emitting mating pheromones and floral scents to attract the insects, especially Japanese beetles. The traps come with a collection bag that makes it easy to dispose of the bad bugs.

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