Hoya 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 Hoya (Hoya carnosa), using what its sources say about pests and diseases, humidity and watering and 3 problems recorded for it.
Sources last read 14 September 2026.
Hoya carnosa, the porcelain flower or wax plant, is a species of flowering plant in the family Apocynaceae, native to East Asia. It is a common house plant grown for its attractive waxy foliage, and sweetly scented flowers. Wikipedia, CC BY-SA 4.0
Native range: S. China to Laos, Japan (S. Kyushu) to Taiwan (subtropical). Also sold as fleshy-leaved wax flower, Honey Plant, porcelain flower, Porcelainflower and Wax Plant.
What Hoya’s sources say that bears on this
- Pests and diseases
- Can be troubled by fungus gnats, mealybugs and banded greenhouse thrips.NC State Extension · read 13 September 2026Mealybugs can occur. Diseases: usually none.RHS · read 13 September 2026
- Humidity
- Most foliage plants prefer more humidity than a heated room gives; succulents are named as an exceptionPenn State Extension · read 11 September 2026
- Watering
- Let the soil dry between waterings. This plant can be shocked by cold water.NC State Extension · read 13 September 2026
How this shows up on a Hoya
Silver-flecked leaves and marked or distorted flowers: an insect pest
Silvery flecks and streaks spread over the leaves of the hoya, peppered with tiny black dots. Flowers may open marked or misshapen.
NC State Extension lists thrips among the pests it may attract. They feed on leaves and in flowers, and hide in buds, which makes them hard to spot.
Telling it apart: Shake a flower or leaf over white paper. Thrips show as tiny slender insects that move.
NC State Extension · read 13 September 2026Sticky leaves and white fluff where they meet the stem: mealybugs
The hoya carries white, cottony specks in its crevices, and growth slows. Leaves beneath the colonies turn sticky and, in time, dull or yellow.
RHS lists mealybugs among the pests it may attract. They feed on sap and shed the excess as sticky honeydew, and a colony tucked into the joints spreads before it is noticed.
Telling it apart: Where the white is. Mealybugs gather in joints and under leaves; a powdery coating across the top of a leaf is mildew.
RHS · read 13 September 2026Tiny dark gnats rising from the potting mix
Small dark flies hover around the hoya and run over the surface of the potting mix. The larvae, thin and white with black heads, live in its top layer.
NC State Extension lists fungus gnats among the pests it may attract. They breed in the top layer of wet potting mix; on an established plant they are mostly a nuisance, on cuttings and seedlings they damage roots.
Telling it apart: Where they fly. Gnats stay around the potting mix; whitefly rises from the leaves.
NC State Extension · read 13 September 2026Possible causes, likeliest first for a Hoya
Most likely fungus gnats, which point at wet potting mix
Ranked higher because Hoya's recorded problems point this way.
Hoya stores water in its own tissue, which makes it more sensitive to wet soil than most leafy plants, so this reading is stronger for it.
- Tiny dark gnats rising from the potting mix NC State Extension
Why: Fungus gnats lay their eggs in moist potting mix, and their larvae feed on organic matter and fungi in it.
What to try:
- Let the top two inches of potting mix dry between waterings; the larvae need it wet.Useful: moisture meter
- Yellow sticky traps near the soil catch the adults and show whether the numbers fall.Useful: sticky traps
What would settle it: Put a slice of raw potato on the soil for a day. Tiny translucent larvae on the underside confirm them.
Most likely mealybugs
Ranked higher because Hoya'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 hoya 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 spider mites
Why: Spider mites feed on individual leaf cells, and each emptied cell shows as a pale speck.
What to try:
- Move the hoya 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 Hoya, still possible
Questions
- What usually causes pests on a Hoya?
- For Hoya: fungus gnats, mealybugs and spider mites. Hoya stores water in its own tissue, which makes it more sensitive to wet soil than most leafy plants, so this reading is stronger for it.
- How can I tell which one it is on my Hoya?
- 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 Hoya's sources say about its pests and diseases?
- NC State Extension: Can be troubled by fungus gnats, mealybugs and banded greenhouse thrips. RHS: Mealybugs can occur. Diseases: usually none.
- What does this look like on a Hoya?
- Silvery flecks and streaks spread over the leaves of the hoya, peppered with tiny black dots. Flowers may open marked or misshapen. Telling it apart: Shake a flower or leaf over white paper. Thrips show as tiny slender insects that move.
Other plants that show pests
String of heartsHard, rounded scale on the undersides of the leaves
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
Something else wrong with the Hoya?
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.