Your greenhouse should be a sanctuary for plants, not a buffet for pests! While these unwanted visitors are inevitable, catching them early and using natural solutions can save your crops without harsh chemicals. Let's explore the usual suspects—and how to send them packing.
The 5 Most Common Greenhouse Pests (and How to Fight Back)
1. Aphids: The Sticky Invaders
Spot them: Clusters of green/black bugs under leaves, sticky honeydew, and curled foliage.
Natural fixes:
- Release ladybugs (Harmonia conformis—our native species) or lacewings.
- Garlic spray: Blend 3 crushed garlic cloves + 1L water + a dash of eco-detergent.
- Natural insecticides: For heavier infestations, try Kendon Insect Destroyer or Pyrethrum Insect Dust—natural pyrethrum-based products that are effective against aphids while being safer for beneficial insects.
- Attract predators: Plant yarrow or dill near entry points.
Local Tip: Order beneficial insects from Bugs for Bugs (QLD) or Biological Services (SA).
2. Whiteflies: The Greenhouse Ghosts
Spot them: Clouds of tiny white insects when you brush plants.
Solutions:
- Yellow sticky traps (hang at plant height).
- Natural sprays: Kendon All Seasons White Oil is effective for whiteflies when applied to the undersides of leaves.
- Encarsia formosa parasitic wasps (works best in temps above 20°C).
- Insect netting: For comprehensive protection, consider installing insect netting to create a physical barrier against whiteflies and other pests.
Warning: Whiteflies spread tomato leaf curl virus—quarantine infested plants!
3. Two-Spotted Mites (Red Spider Mites)
Spot them: Yellow speckles on leaves + fine webbing (worst in hot, dry areas).
Solutions:
- Mist plants daily (mites hate humidity).
- Phytoseiulus persimilis predatory mites (thrive in 15-30°C).
- Natural treatments: Kendon All Seasons White Oil can help control mite populations when applied regularly.
- Wipe leaves with damp cloth + a few drops of eucalyptus oil.
Did You Know? Mites explode in population during heatwaves—shade cloth can help reduce heat stress and mite populations.
4. Slugs & Snails: The Slimy Midnight Raiders
Spot them: Ragged holes + glittery trails (especially in QLD/NSW coastal areas).
Solutions:
- Copper barriers: Copper Tape (4 metre) or Copper Slug Trap (10 metre) create an effective barrier that deters slugs and snails—completely chemical-free and long-lasting.
- Organic baits: For larger areas, Eradicate Eco Snail & Slug Bait (available in 1KG, 2.5KG, and 25KG sizes) is certified organic, pet-safe, and rainfast—perfect for sustainable pest control.
- Beer traps (use a cheap stubby buried to the rim).
- Handpick at dusk (a torchlit 'slug patrol' works!).
Native Alternative: Encourage blue-tongue lizards with rock piles near your greenhouse.
5. Fungus Gnats: The Soil Nuisance
Spot them: Tiny black flies buzzing around potting mix.
Solutions:
- Let soil dry out between waterings.
- Sand topping: 1cm of sharp sand over potting mix blocks egg-laying.
- Mosquito Dunk tablets (contain BTI—approved for AU organic gardening).
Prevention: Build a Resilient Greenhouse
🌿 Companion Planting for Our Climate
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Native companions:
- Lemon myrtle deters flies.
- Bush basil repels thrips.
- Trap crops: Plant nasturtiums away from veggies to lure aphids.
🌱 Soil Health
- Amend soil with kangaroo manure (low-odor and nutrient-rich).
- Boost microbes with worm tea from your compost bin.
🐞 Beneficial Bugs Down Under
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Dedicate a corner to flowering natives (Scaevola, Grevillea) to attract:
- Hoverflies (aphid eaters).
- Predatory wasps (whitefly assassins).
Pro Tip: Avoid pesticides—they kill good bugs too!
🧹 Greenhouse Hygiene
- Disinfect with vinegar (1:3 vinegar/water) between seasons.
- Check plants weekly—early mornings are best for pest spotting.
When to Call for Backup
For severe infestations (like Queensland fruit fly), early detection is key. Consider using Codling Moth Lures or Light Brown Apple Moth Lures to track pest populations before they become a problem. For serious outbreaks, consult your state's agriculture department:
- NSW: DPI Biosecurity
- QLD: Business Queensland
Need comprehensive pest protection? Consider installing insect netting or building a net house for complete pest exclusion. For heat and pest management, shade cloth can help regulate temperature while providing additional protection.
Shop our full range of pest control solutions: From copper barriers and organic baits to natural insecticides and monitoring tools, browse our complete pest & insect control collection for all your greenhouse pest management needs.
