Sweet basil pests, webbing or sticky leaves: causes and what to do
6 results in the diagnosis tree begin with pests, 5 of them marked likely when the answers fit. They are ordered here for Sweet basil (Ocimum basilicum), using what its sources say about pests and diseases and humidity and 2 problems recorded for it.
Sources last read 18 September 2026.
Basil, also called great basil, is a culinary herb of the family Lamiaceae (mints). It is a tender plant and is used in cuisines worldwide. Wikipedia, CC BY-SA 4.0
Native range: Trop. & Subtrop. Asia to N. Australia (seasonally dry tropical). Also sold as Basil, common basil, Genovese Basil, Greek royal, kiss-me-Nicholas and lemon basil.
What Sweet basil’s sources say that bears on this
- Pests and diseases
- Can be troubled by Japanese beetle, aphids, and slugs and snails. Diseases: basil downy mildew.NC State Extension · read 13 September 2026Can be troubled by sage leafhopper, snails, slugs and aphids. Diseases: powdery mildews can occur.RHS · read 13 September 2026
- Humidity
- ASHRAE recommends indoor relative humidity between 30% and 60%Penn State Extension · read 13 September 2026
How this shows up on a Sweet basil
Small insects that jump when the leaves are disturbed
Touching the sweet basil sends small, wedge-shaped insects leaping. The leaves they fed on are mottled pale.
RHS lists leafhoppers among the pests it may attract. They suck sap from the undersides, which leaves pale dead cells on the surface above.
Telling it apart: Whether the insects jump. Leafhoppers leap; whitefly flies up in a cloud.
RHS · read 13 September 2026Sticky buds and shoot tips crowded with small insects
Aphids gather on the undersides of new leaves and around buds on the sweet basil, leaving honeydew and shed skins behind.
RHS lists aphids among the pests it may attract. They feed on the sap of soft new growth, which distorts it, and they multiply quickly without mating.
Telling it apart: Where they sit. Aphids crowd soft tips and buds; scale sits still on older stems.
RHS · read 13 September 2026Possible causes, likeliest first for a Sweet basil
Most likely aphids
Ranked higher because Sweet basil's recorded problems point this way.
- Sticky buds and shoot tips crowded with small insects RHS
Why: Aphids cluster on soft new growth and flower buds, where the sap is easiest to reach.
What to try:
- Rub them off with fingers, or rinse them off in a sink or shower.
- Repeat every few days while new ones appear.
What would settle it: Look for the pale shed skins among the insects. Aphids molt as they grow, and the skins are left behind in the colony.
Most likely spider mites
Why: Spider mites feed on individual leaf cells, and each emptied cell shows as a pale speck.
What to try:
- Move the sweet basil away from other plants.
- Wash the leaves, top and underside, with a strong spray of water in a shower or sink.
What would settle it: Hold a sheet of white paper under a leaf and tap the leaf. Tiny specks that move across the paper are mites.
Most likely mealybugs
Why: Mealybugs are soft insects that cover themselves in white wax, which gives the cottony look.
What to try:
- Move the sweet basil away from other plants.
- Wipe off every insect you can see with a cotton swab dipped in rubbing alcohol, testing a single leaf first.
What would settle it: Touch a tuft with a cotton swab. If a small, pale, oval insect is underneath, it is a mealybug.
Less likely for a Sweet basil, still possible
Questions
- What usually causes pests on a Sweet basil?
- For Sweet basil: aphids, spider mites and mealybugs.
- How can I tell which one it is on my Sweet basil?
- What can you see? Fine webbing, and tiny pale speckles on the leaves; White, cottony tufts in the leaf joints; Small brown or pale bumps on stems and leaves that do not move; Clusters of small, soft insects on the new growth; Tiny dark flies around the soil; Sticky, shiny residue, but no insect I can see.
- What do Sweet basil's sources say about its pests and diseases?
- NC State Extension: Can be troubled by Japanese beetle, aphids, and slugs and snails. Diseases: basil downy mildew. RHS: Can be troubled by sage leafhopper, snails, slugs and aphids. Diseases: powdery mildews can occur.
- What does this look like on a Sweet basil?
- Touching the sweet basil sends small, wedge-shaped insects leaping. The leaves they fed on are mottled pale. Telling it apart: Whether the insects jump. Leafhoppers leap; whitefly flies up in a cloud.
Other plants that show pests
AlocasiaFine pale speckling on the leaves, then webbing at the tips: spider mites
Aloe veraSticky leaves and immobile shell-like insects on the stems
Areca palmDull, finely mottled fronds and faint webs: spider mites
Arrowhead plantCurled, sticky new leaf blades with green or black insects: aphids
Asparagus fernCurled, sticky new fronds with green or black insects: aphids
Bird's nest fernSticky leaves and immobile shell-like insects on the stems
Something else wrong with the Sweet basil?
What this does not cover
This page orders a decision tree's results using a plant's sourced care. It has not seen your plant, its pot or its window, and two problems at once are common: that is the usual reason a confident answer turns out wrong. The questions in the diagnosis tool narrow it further than a list can.