Wax begonia 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 Wax begonia (Begonia semperflorens), using what its sources say about pests and diseases and humidity and 5 problems recorded for it.
Sources last read 18 September 2026.
Native range: S. Brazil to NE. Argentina (seasonally dry tropical). Also sold as bedding begonia.
What Wax begonia’s sources say that bears on this
- Pests and diseases
- Can be troubled by aphids, vine weevil, greenhouse thrips, mites, mealybugs and caterpillars. Diseases: rhizome rot, stem rot, powdery mildews and grey moulds.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 Wax begonia
Clusters of small soft insects on the shoot tips and buds: aphids
Green, black or pale insects crowd the soft tips and buds of the wax begonia. New leaves curl, and white cast skins collect below.
RHS lists aphids among the pests it may attract. They favor tender tips and buds, so the damage concentrates where the plant is growing.
Telling it apart: Where they sit. Aphids crowd soft tips and buds; scale sits still on older stems.
RHS · read 13 September 2026Ragged, eaten leaves and rolled leaves: an insect pest
Chewed leaves on the wax begonia come with green or brown caterpillars nearby, often active at night.
RHS lists caterpillars among the pests it may attract. Moth and butterfly larvae eat leaf tissue, and some fold leaves around themselves for shelter.
Telling it apart: Droppings. Caterpillars leave dark pellets below the damage; slugs leave slime.
RHS · read 13 September 2026Silvery streaks with black specks on the leaves: thrips
Silvery flecks and streaks spread over the leaves of the wax begonia, peppered with tiny black dots. Flowers may open marked or misshapen.
RHS lists thrips among the pests it may attract. The black dots are their droppings, and the silver is air where the cell contents were.
Telling it apart: The black specks. Silvering with black dots is thrips; pale dots without them point at mites.
RHS · read 13 September 2026Sticky leaves and white fluff where they meet the stem: mealybugs
Clusters of white wax sit where each leaf joins the stem and along the undersides of the wax begonia. Lifted with a cotton swab, each tuft holds a soft, pale insect, and the leaves below are sticky.
RHS lists mealybugs among the pests it may attract. The wax keeps them dry and hard to reach, so they multiply in the sheltered joints of the plant.
Telling it apart: Whether the white comes with stickiness. Mealybugs leave honeydew; dust and mildew do not.
RHS · read 13 September 2026Sudden wilting from a root pest: vine weevil grubs in the potting mix
The wax begonia wilts and collapses although it has been watered. In the potting mix are cream, C-shaped grubs with brown heads, and few roots remain.
RHS lists vine weevil among the pests it may attract. The adults feed at night and hide by day, so the notched edges are often the only sign above ground.
Telling it apart: Whether the plant is loose. Grub damage leaves a plant that lifts from its pot with few roots.
RHS · read 13 September 2026Possible causes, likeliest first for a Wax begonia
Most likely mealybugs
Ranked higher because Wax begonia's recorded problems point this way.
- Sticky leaves and white fluff where they meet the stem: mealybugs RHS
Why: Mealybugs are soft insects that cover themselves in white wax, which gives the cottony look.
What to try:
- Move the wax begonia 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.
Most likely aphids
Ranked higher because Wax begonia's recorded problems point this way.
- Clusters of small soft insects on the shoot tips and buds: aphids 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 wax begonia 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.
Less likely for a Wax begonia, still possible
Questions
- What usually causes pests on a Wax begonia?
- For Wax begonia: mealybugs, aphids and spider mites.
- How can I tell which one it is on my Wax begonia?
- 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 Wax begonia's sources say about its pests and diseases?
- RHS: Can be troubled by aphids, vine weevil, greenhouse thrips, mites, mealybugs and caterpillars. Diseases: rhizome rot, stem rot, powdery mildews and grey moulds.
- What does this look like on a Wax begonia?
- Green, black or pale insects crowd the soft tips and buds of the wax begonia. New leaves curl, and white cast skins collect below. Telling it apart: Where they sit. Aphids crowd soft tips and buds; scale sits still on older stems.
- Is Wax begonia safe to handle while I check it?
- Its sources list it as toxic to cats and dogs. Wash your hands after handling the roots or sap, and keep trimmings away from pets.
Other plants that show pests
African violetIrregular notches bitten from leaf edges by an insect pest
Barberton daisyCurled, sticky new leaves with green or black insects: aphids
Bearded irisRagged holes and slime trails: a slug or snail pest
Bigleaf hydrangeaClusters of small soft insects on the shoot tips and buds: aphids
Bird of paradiseDull, finely mottled leaves and faint webs: spider mites
Blue passion flowerPale stippled leaves and tiny moving dots underneath: a mite pest
Something else wrong with the Wax begonia?
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.