Most Common Garden Pests in the Pacific Northwest and How to Eradicate or Manage Them

The Pacific Northwest, with its mild, temperate climate, is a beautiful place to grow a wide variety of plants. However, this favorable environment also attracts a range of garden pests that can threaten the health and beauty of your garden. Here’s a look at the most common garden pests in the Pacific Northwest and practical tips on how to manage or eradicate them.

1. Slugs and Snails

Appearance: Slugs and snails are soft-bodied, slimy creatures that love moist, shaded areas. Slugs are usually gray or black, while snails have hard, spiraled shells that can range in color from brown to tan.

Damage: These pests feed on tender plant leaves, leaving behind ragged holes. They are particularly harmful to seedlings, leafy vegetables, and delicate flowers like hostas.

Control:

• Handpicking: Go out in the early morning or evening and collect them by hand.
• Natural Predators: Encourage birds, frogs, or beetles to visit your garden, as they will help control slug populations.
• Barriers: Sprinkle diatomaceous earth or crushed eggshells around your plants. The sharp edges of these substances will deter slugs and snails.
• Beer Traps: Bury a shallow container and fill it with beer. Slugs are attracted to it and drown in the liquid.
• Slug Baits: Organic slug bait with iron phosphate is an effective and pet-safe option.

2. Aphids

Appearance: Aphids are small, soft-bodied insects that come in a variety of colors, including green, yellow, and black. They are usually found in clusters on the undersides of leaves.

Damage: Aphids suck sap from plants, weakening them, and causing yellowing of leaves and stunted growth. They also excrete a sticky substance called honeydew, which can lead to the growth of sooty mold.

Control:

• Water Spray: Use a strong jet of water to dislodge aphids from your plants.
• Natural Predators: Encourage ladybugs, lacewing larvae, and parasitic wasps, which feed on aphids.
• Insecticidal Soap: Apply a diluted solution of insecticidal soap or neem oil to the affected areas, ensuring you cover both the tops and bottoms of leaves.
• Companion Planting: Plant garlic, chives, or marigolds near susceptible plants, as they are known to repel aphids.

3. Spider Mites

Appearance: Spider mites are tiny arachnids that are difficult to see with the naked eye. They are usually red or green and are often found on the underside of leaves.

Damage: These pests suck sap from plants, causing leaves to appear speckled, yellowed, and stippled. In severe cases, the leaves may curl and fall off, and the plant may die.

Control:

• Water Spray: Regularly rinse the plants with a strong spray of water to wash away spider mites.
• Insecticidal Soap: Apply insecticidal soap or neem oil directly to the affected areas.
• Encourage Predators: Introduce predatory mites, which feed on spider mites.
• Avoid Over-fertilizing: Excessive nitrogen can make plants more vulnerable to spider mites, so be mindful of your fertilizer use.

4. Cabbage Worms

Appearance: Cabbage worms are green caterpillars that are commonly found on plants like cabbage, broccoli, and kale. They are the larvae of the cabbage butterfly, which has white wings with black spots.

Damage: These pests chew holes in the leaves of cabbage family plants, which can severely damage the crop.

Control:

• Handpicking: Regularly inspect your plants for worms and pick them off by hand.
• Row Covers: Use floating row covers to physically block butterflies from laying eggs on your plants.
• Natural Pesticides: Bacillus thuringiensis (Bt) is a natural bacteria that targets caterpillars without harming beneficial insects.
• Diatomaceous Earth: Sprinkle diatomaceous earth around plants to deter the caterpillars.

5. Cutworms

Appearance: Cutworms are the larvae of various moth species and are usually pale or brown, with a soft, greasy appearance. They curl up when disturbed and often hide during the day.

Damage: Cutworms chew through the stems of young plants, causing them to fall over and die. They are particularly destructive to seedlings.

Control:

• Physical Barriers: Place collars made from cardboard or plastic around young plant stems to protect them.
• Handpicking: Inspect your plants in the evening and remove any visible cutworms.
• Diatomaceous Earth: Sprinkle diatomaceous earth around the base of plants to deter cutworms.

6. Thrips

Appearance: Thrips are tiny, slender insects that are often yellow or black. They can be hard to spot, but you may notice silver streaks or discoloration on affected plants.

Damage: Thrips feed on plant cells, causing silvery streaks, distorted leaves, and sometimes black specks from their excrement. They are also known to transmit plant viruses.

Control:

• Sticky Traps: Place yellow or blue sticky traps around your garden to capture adult thrips.
• Water Spray: A strong spray of water can dislodge thrips from your plants.
• Insecticidal Soap: Apply insecticidal soap or neem oil directly to affected areas.
• Remove Infected Plants: If an infestation is severe, remove and destroy the most heavily infested plants to prevent the spread of thrips.

7. Japanese Beetles

Appearance: Japanese beetles are shiny, metallic green beetles with copper-colored wings.

Damage: These beetles feed on the leaves of many plants, including roses, beans, and fruit trees, leaving behind skeletonized foliage.

Control:

• Handpicking: Pick beetles off plants in the early morning when they are less active.
• Pheromone Traps: Use traps to reduce the adult beetle population in your garden.
• Neem Oil: Apply neem oil to deter beetles from feeding on your plants.
• Natural Predators: Encourage birds, such as chickens, to eat the beetles.

Conclusion

The Pacific Northwest’s lush environment supports a wide variety of garden pests, but with the right strategies, you can keep them in check. Regular monitoring, using natural predators, and applying organic treatments will help you maintain a healthy, pest-free garden. For help with garden projects, call Levy’s Lawns and Landscaping at (360) 876-6567.