Pest & Plant Disease Troubleshooting
How to Identify the Most Common Garden Pests
Spot the pests behind holey leaves, sticky residue and stunted growth — what to look for, which plants they target, and what to do about each one.
Most pest damage has a distinct signature once you know what to look for — sticky leaves, ragged holes, silvery trails, or tiny moving dots on the underside of a leaf. Correct identification is the difference between a five-minute fix and losing the plant.
Identifying the usual suspects
| Pest | Signs | Plants most affected | What to do |
|---|---|---|---|
| Aphids | Clusters on new shoots, sticky honeydew, curled leaves | Roses, vegetables, most soft growth | Spray off with water; encourage ladybirds |
| Spider mites | Fine webbing, stippled pale leaves | Tomatoes, beans, houseplants in dry air | Increase humidity; wipe leaves; insecticidal soap |
| Slugs & snails | Ragged holes, slime trails, worst at night | Seedlings, salad, hostas | Beer traps, copper tape, hand-pick at dusk |
| Mealybugs | White cottony clumps in leaf joints | Houseplants, citrus | Dab with rubbing alcohol on a cotton bud |
| Fungus gnats | Tiny black flies near soil, larvae in top layer | Overwatered pots, houseplants | Let soil dry between waterings; sticky traps |
A simple inspection routine
Check the undersides of leaves
Most pests hide where you’re least likely to look. Turn a few leaves over weekly, especially on new growth.
Look for the damage pattern, not just the bug
Holes, stippling, webbing and sticky residue each point to a different pest even if you never see it moving.
Isolate anything badly affected
Move a heavily infested container away from healthy plants while you deal with it, especially indoors, to stop pests spreading.
Start with the mildest treatment
A strong jet of water or wiping leaves by hand solves most small infestations without reaching for a spray at all.
Frequently asked questions
How do I know if it's a pest or a disease?
Pests usually leave physical evidence — holes, webbing, sticky residue, or visible insects. Diseases tend to show as discoloured patches, spots, wilting or powdery coatings without any bite marks.
Are pests worse in containers than in open ground?
Not inherently, but container plants are often stressed by inconsistent watering, which makes them more attractive to pests like spider mites and aphids — consistent watering is itself a form of pest prevention.
Do I need to treat a pest if I only see a few?
Usually not urgently — a handful of aphids or one slug rarely does lasting damage. Start monitoring weekly and act once numbers climb or damage spreads.