Most Common Garden Pests in Vegetable Garden Beds
Garden pests can be the toughest challenge for any gardener, especially when first starting. These pests can wreak havoc on various types of crops, but leafy vegetables are often the most affected. Many of the following pests target leafy vegetables, damaging the plants and could kill the plant if not quickly treated.
The Most Common Garden Pests and Prevention Methods
These are small, common garden pests that suck the sap from your plants. Due to their size, it can be difficult to identify aphids in small numbers, often only being noticed once a plant is infested. Once infested, aphids can quickly damage and kill plants.
Aphids can be many colors, including green, black or pink. They target newly growing, soft plants to feed on. When aphids multiply, they begin fighting over position they can be found on the plant’s stem, under leaves, even on the fruit.
As aphids feed and multiple, a sticky honeydew is generated that increases mold growth. Aphids commonly produce winged generations which fly off to the next garden.
Signs of Aphids:
- Sticky residue on plants
- Mold growth
- Reduced plant quality
- Small spots on plants (can look like tiny dots)
Many gardeners will regularly check their plants, ready to pinch off any aphids before they multiply. However, due to their size and not all of us have 20/20 vision, there are some other ways to reduce these garden pests.
- Aphids can usually be removed with a good hosing or using a spray bottle to knock them off plants.
- Increase native parasites and predators to manage aphids. These include: lacewings, aphid midges, and lady bugs.
- Using floating row cover plants, when possible.
- Spray plants with garlic or hot pepper repellants (ensure repellant will not damage your plants first, of course).
Application of insecticidal soap, horticultural oil or neem.
The whitefly appears similar to a white ‘moth’, but is not actually a fly. Whiteflies are more related to aphids and hide under the leaves which make them a challenge to manage. To increase this challenge, whiteflies can quickly multiple. During the summer, a whitefly matures from egg to adult in about 16 days.
The whitefly damages your plants in a couple ways:
This is caused from sucking sap directly from the plants. This will cause yellowing and shriveling leaves. When there are multiple whiteflies, it can kill plants.
The adult whitefly may transmit various viruses between a diseased and healthy plant. Like aphids, the whitefly secrets “honeydew”, which leaves sticky residue on plants. This honeydew aids in fungus growth known as “sooty mold”, which result in leaves appearing dirty and black. Although harmless itself, it prevents sun from reaching plant surfaces, increasing plant stress.
Signs of Whiteflies:
- The most common way to identify these garden pests is by disturbing plants – whiteflies will flutter around.
- Whitefly nymphs (prior to growing their wings) have oval bodies.
The best organic method to prevent whiteflies, like with other common garden pests, is to understand beneficial insects. For example, parasitic wasps use the body of whiteflies for laying eggs, which kills the whitefly and parasitic wasps are unable to sting people.
Plant flowering plants that attract beneficial insects and natural predators, including spiders, ladybugs, and lacewings.
Place sticky traps around the garden for early detection.
Always inspect new plants before purchasing, avoid buying plants that are infected.
Already got a Whitefly infestation?
Here are a few ways to gain control of your garden:
- Spray plants with a stream of water to remove whiteflies and honeydew. When done in early morning, the adult whitefly will be slower, use a vacuum to capture fluttering whiteflies. Empty the vacuum into a sealable plastic bag and discard.
- Prune and discard of severely infested parts of plants.
- Increase beneficial insects, such lady bugs. A single black lady bug (Delphastus) is able to consume 150 whitefly eggs per day.
These garden pests leave behind a white cotton style coating on plants, which is often the biggest sign you have mealybugs. The mealybug is more common in outdoor gardens located in the south, and houseplants in the north.
Mealybugs have a soft body, which is why they depend on their cotton-style coat to protect them. They are most active when young, and slow down to eat when grown.
The mealybug sucks the sap out of plants, creating a honeydew which they cover themselves in. Their cotton style coat not only protects them from predators, but various control products too. However, with persistence they can be managed.
Signs of Mealybugs:
Sticky residue on plants (honeydew)
White cotton looking patches
The first step is to keep plants healthy, as mealybugs target weak, stressed and hungry plants.
Mealybugs in Small Numbers:
Only see a few mealybugs? Use a stream of water to knock them off, similar to aphids and the whitefly. Repeat as needed to control a small issue from becoming a larger problem.
Mealybugs in Large Numbers:
When the mealybugs have taken over, it can be harder to eliminate them due to the cotton-style coating, which protects these garden pests from various sprays. However, there are a couple approaches to regain control of your vegetable garden (or rose garden):
Systemic Bug Control
The following products have been known to absorb into the cotton-style coating of mealybugs. Also, they absorb into plant leaves, killing future mealybugs up to 4 weeks:
- Ortho Flower, Fruit & Vegetable Insect Killer
- Ortho Rose & Flower Insect Killer (Ready to Use)
This method smothers the mealybugs using a product such as Ortho Fruit Tree Spray.
Note: Always check to ensure a product is safe for your type of plants before purchasing.
These garden pests are roughly the size of a sewing needle, and can be found worldwide eating on all types of plants. Depending on the location, they may be referred to as thunderflies or thysanoptera.
Thrips feed on plants by sucking the sap, which can result in plant damage itself. However, the real danger is thrips transmitting viruses between a diseased plant and healthy plant.
Thrips use bark, plant debris or other types of materials to hibernate through winter, becoming active again during early spring, laying eggs within plant tissues. It only takes 3 to 5 days for eggs to hatch, with nymphs feeding on plants for 1 to 3 weeks prior to molting. Depending on the location and weather conditions, Thrips can have up to 15 generations per year.
Without a magnifying glass, it can be hard to detect thrips in early stages, appearing as small dark slivers on the plant. Under a magnifying glass, they have a lobster look to them.
Signs of Thrips:
Thrips can range in color, from brown, black, to yellow. Thrips nymphs are often yellow or light green and may have red eyes.
When disturbed, thrips often fly or leap off using fringed, narrow wings.
See dark slivers on plants? Hold a white piece of paper under the plant and try to shake the slivers off, making them easier to see.
Plants have streaks or small white patches.
- Use blue or yellow sticky traps for early detection.
- Plant flowers to attract beneficial insects, such as lacewings, lady bugs, and pirate bugs.
- Lay cloth under plants, then gently shake plants to jar loose the thrips.
- Use insecticidal soap to kill infestations.
- Apply diatomaceous earth (DE) under leaves – use as a last resort.
Note: For thrips on fruit trees, spray the trees with dormant oil.
5. Cabbage Looper
These garden pests are common among cabbage plants. They are found throughout the United States, Mexico, even Canada. They look like little green caterpillars. Maintaining control over cabbage loopers is important to prevent holes and rotting spots in your plants.
Larvae of the cabbage looper matures into a thick green caterpillar that has white stripes on the side. The head is thinner than the rest of the body. When fully matured, cabbage loopers can be 2-inches long. After the cabbage looper pupates, it turns into a gray-brown moth.
These pests damage plants as they chew the foliage and leave holes and jagged edges on leaves. Luckily, this common garden pest is large enough to spot visually.
- Increase beneficial predators
- Place row covers at time of planting.
The safest way to remove cabbage loopers is by visually inspecting plants and manually removing them. The best time to look is in the early morning or late evening as temperatures are the coolest. Pick off all of them you can see from the plants, and discard of them as you wish. One method is to drop them into hot soapy water.
Inspect under leaves for cabbage looper eggs, gently scrape them off into a container if found. Eggs are laid in ridged rows.
Organic cabbage looper pesticides, such as Bacillus thuringiensis (Bt).
Try to avoid using chemicals, as they can also kill the beneficial predators.