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High Priority Pests

Plant Pest Diagnosis

Identify common houseplant pests by visible signs, damage patterns, and urgency. Compare mites, aphids, gnats, scale, whiteflies, and mealybugs.

Plant Pest Diagnosis example

Quick answer

Most cases come down to pattern, spread, and urgency.

For visible insects, sticky residue, webbing, or pest damage on plants, match the visible pattern first, then check whether the cause is environmental, watering-related, pest-related, disease-related, or part of normal plant growth.

Detection Tips

  • Quarantine any plant with visible pests, webbing, sticky residue, or unexplained stippling.
  • Check leaf undersides, stem joints, soil surface, and new growth with bright light.
  • Repeat treatment cycles because many pest eggs survive the first treatment.
Spider Mites diagnosis pattern
High Priority

Primary cause: Tiny spider-like pests

Spider Mites

Fine webbing on leaves, tiny yellow or white stippling, and microscopic moving dots on leaf undersides.

Common causes

Dry indoor airStressed plantsHot conditionsPoor air circulation

Treatment steps

  1. 1 Increase humidity immediately (60%+)
  2. 2 Spray with insecticidal soap daily
  3. 3 Apply neem oil treatment
  4. 4 Quarantine affected plant
  5. 5 Improve air circulation

When to worry

Spider mites spread extremely fast - treat immediately upon detection.

Commonly affected plants

Almost all houseplantsStressed plantsPlants in dry conditions
Aphids diagnosis pattern
Medium Priority

Primary cause: Soft-bodied insects

Aphids

Small green, black, or white insects clustering on new growth and leaf undersides, often with sticky honeydew residue.

Common causes

New plant introductionOutdoor plants brought insideOverfeeding with nitrogenWeak plant immunity

Treatment steps

  1. 1 Rinse off with strong water spray
  2. 2 Apply insecticidal soap spray
  3. 3 Use neem oil treatment
  4. 4 Introduce beneficial insects if outdoors
  5. 5 Remove heavily infested leaves

When to worry

If population explodes or spreads to other plants within days.

Commonly affected plants

New growth on any plantSoft-stemmed plantsRecently fertilized plants
Fungus Gnats diagnosis pattern
Low Priority

Primary cause: Larvae in moist soil

Fungus Gnats

Small dark flies around soil surface, larvae visible in soil, and adults flying when the plant is disturbed.

Common causes

OverwateringPoor soil drainageOrganic matter decompositionHigh soil moisture

Treatment steps

  1. 1 Reduce watering frequency significantly
  2. 2 Let soil dry out between waterings
  3. 3 Apply yellow sticky traps
  4. 4 Top-dress soil with sand or perlite
  5. 5 Use mosquito dunks in water

When to worry

If larvae damage roots or adult population becomes overwhelming.

Commonly affected plants

Overwatered plantsPlants in organic-rich soilRecently repotted plants
Scale Insects diagnosis pattern
High Priority

Primary cause: Armored or soft scale

Scale Insects

Small brown, white, or clear bumps on stems and leaves, sticky honeydew, and yellowing leaves.

Common causes

Introduction from new plantsStress from poor conditionsIndoor environments favor scaleLack of natural predators

Treatment steps

  1. 1 Scrape off scale with fingernail or soft brush
  2. 2 Apply rubbing alcohol with cotton swab
  3. 3 Use systemic insecticide for severe cases
  4. 4 Quarantine plant immediately
  5. 5 Monitor weekly for new infestations

When to worry

Scale can kill plants - immediate and persistent treatment required.

Commonly affected plants

FicusCitrus plantsPalmsSucculents
Whiteflies diagnosis pattern
Medium Priority

Primary cause: Small white flying insects

Whiteflies

Tiny white insects fly up when the plant is disturbed, with sticky honeydew on leaves and yellowing foliage.

Common causes

Warm indoor conditionsIntroduction from greenhouse plantsPoor air circulationStressed plants

Treatment steps

  1. 1 Use yellow sticky traps extensively
  2. 2 Vacuum flying adults in morning
  3. 3 Apply insecticidal soap spray
  4. 4 Use reflective mulch around plant
  5. 5 Improve air circulation

When to worry

If population establishes and spreads to multiple plants.

Commonly affected plants

Tropical plantsFlowering plantsGreenhouse plantsSoft-leaved plants
Mealybugs diagnosis pattern
High Priority

Primary cause: White cottony insects

Mealybugs

White, cottony clusters in leaf joints and stem crevices, sticky honeydew, and plant weakness.

Common causes

Introduction from infected plantsWarm humid conditionsHidden in plant crevicesStress from overwatering

Treatment steps

  1. 1 Dab with rubbing alcohol on cotton swab
  2. 2 Rinse thoroughly with water spray
  3. 3 Apply systemic insecticide
  4. 4 Quarantine affected plant
  5. 5 Check all nearby plants weekly

When to worry

Mealybugs can kill plants and spread rapidly - treat aggressively.

Commonly affected plants

SucculentsTropical plantsOrchidsPlants with many crevices

Related Plant Clinic Guides

Compare nearby symptoms if this pattern does not exactly match your plant.

Medium Priority Watering

Yellow Leaves

Leaves turning yellow, fading, or dropping earlier than expected.
Low Priority Environment

Brown Leaf Tips

Leaf tips turning brown, dry, or crispy while the rest of the plant survives.
High Priority Root Issues

Wilting

Stems and leaves drooping even after normal watering routines.