Burro's tail 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 Burro's tail (Sedum morganianum), using what its sources say about pests and diseases, humidity and watering and 2 problems recorded for it.
Sources last read 14 September 2026.
Sedum morganianum, the donkey tail or burro's tail, is a species of flowering plant in the family Crassulaceae, native to southern Mexico. It is a succulent perennial producing trailing stems up to 60 cm (24 in) long, with fleshy blue-green leaves and terminal pink to red flowers in summer. Wikipedia, CC BY-SA 4.0
Native range: Mexico (Veracruz, Puebla, Chiapas) (seasonally dry tropical). Also sold as donkey tail, donkey's tail, horse's tail, lamb's tail and Stonecrop.
What Burro's tail’s sources say that bears on this
- Pests and diseases
- Diseases: southern blight.NC State Extension · read 13 September 2026Mealybugs, scale insects and vine weevil grubs can attack it. Disease risks: crown and root rots, both fungal and bacterial.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 13 September 2026
- Watering
- Use lukewarm water, and water less in winter. Let the soil dry between waterings, and feed lightly once or twice in the growing season.NC State Extension · read 13 September 2026In the growing season, water generously and feed monthly with a liquid fertiliser at half strength; give little water in winter.RHS · read 13 September 2026
How this shows up on a Burro's tail
Hard, rounded scale on the undersides of the leaves
Rows of small, hard scales sit where the veins of the Burro's tail are thickest, and the surface below them is glossy with honeydew.
RHS lists scale insects among the pests it may attract. The insect settles under a waxy shell and feeds on sap for life, so a colony builds quietly along the stems.
Telling it apart: Flick a bump with a fingernail. Scale comes away and leaves a mark; a natural bump on the stem does not move.
RHS · read 13 September 2026Small white woolly insects tucked into the leaf joints
The Burro's tail 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: Wipe a tuft with a cotton swab. An insect smears or crawls; a mineral deposit or a hair does not.
RHS · read 13 September 2026Possible causes, likeliest first for a Burro's tail
Most likely mealybugs
Ranked higher because Burro's tail's recorded problems point this way.
- Small white woolly insects tucked into the leaf joints RHS
Why: Mealybugs are soft insects that cover themselves in white wax, which gives the cottony look.
What to try:
- Move the burro's tail 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 scale insects
Ranked higher because Burro's tail's recorded problems point this way.
- Hard, rounded scale on the undersides of the leaves RHS
Why: Scale insects settle in one place under a hard or waxy shell and feed on sap.
What to try:
- Move the burro's tail away from other plants.
- Scrape the scales off with a fingernail or a soft brush, then wipe the stems and leaves.
What would settle it: Push a bump gently with a fingernail. Scale comes away and leaves a mark; a bump that is part of the burro's tail does not move.
Most likely fungus gnats, which point at wet potting mix
Ranked higher for Burro's tail because of what its sources say.
Burro's tail 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.
- Well-drained RHS · read 13 September 2026
- Loam, Sand, Chalk; pH Alkaline or Neutral RHS · read 13 September 2026
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.
Less likely for a Burro's tail, still possible
Questions
- What usually causes pests on a Burro's tail?
- For Burro's tail: mealybugs, scale insects and fungus gnats.
- How can I tell which one it is on my Burro's tail?
- 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 Burro's tail's sources say about its pests and diseases?
- NC State Extension: Diseases: southern blight. RHS: Mealybugs, scale insects and vine weevil grubs can attack it. Disease risks: crown and root rots, both fungal and bacterial.
- What does this look like on a Burro's tail?
- Rows of small, hard scales sit where the veins of the Burro's tail are thickest, and the surface below them is glossy with honeydew. Telling it apart: Flick a bump with a fingernail. Scale comes away and leaves a mark; a natural bump on the stem does not move.
Other plants that show pests
Jade plantCurled, sticky new leaves with green or black insects: aphids
Mexican snowballSticky buds and shoot tips crowded with small insects
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
Something else wrong with the Burro's tail?
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.