YEAR-ROUND
Citrus mealybug
Fluffy white wax in the leaf joints and other sheltered places. It breeds all year indoors.
Crop hub · Indoors · Home garden
Succulents & cacti
The RHS says glasshouse mealybugs are found mainly on greenhouse plants and houseplants, especially cacti and succulents, and UC IPM names cactus and jade among the houseplants that often carry them. They usually show first as fluffy white wax in the leaf joints or other sheltered places.
The harder problems are below the compost. Root mealybugs and root aphids leave white wax on the roots, and vine weevil grubs bore into the stem bases of cacti and succulents. A plant that stalls, yellows or wilts in moist compost for no visible reason should be tipped out of its pot and its roots checked.
crop context · potted cacti and succulents
What attacks succulents, above and below the compost
WHEN REPOTTING
Root mealybugs
White, waxy patches on the roots and root ball. Harder to control than the mealybugs on stems.
ReleaseNothing proven to releaseIsolate or discard the plant
SEP–MAR
Vine weevil
C-shaped white grubs in the compost eat roots and bore into stem bases; container plants can wilt and die.
WHEN REPOTTING
Root aphids
Small aphids coated in white wax on the roots; plants stunt and wilt for no visible reason.
ReleaseNothing proven to releaseWash the roots and repot
WET COMPOST
Springtails
Harmless decomposers. Clemson treats them as a sign of overwatering, so on succulents they point to compost staying too wet.
ReleaseNothing to releaseLet the compost dry out
IN THE COMPOST
Soil mites
Tiny mites in the potting mix, mostly decomposers. Not spider mites, and no treatment is needed.
ReleaseNothing to releaseNo treatment needed
Season calendar
INDOORS AND POTS · NORTHERN HEMISPHERE · QUALITATIVE| J | F | M | A | M | J | J | A | S | O | N | D | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mealybugs (breed all year, slower in winter) | Jan: Building | Feb: Building | Mar: Pest pressure high | Apr: Pest pressure high | May: Pest pressure high | Jun: Pest pressure high | Jul: Pest pressure high | Aug: Pest pressure high | Sep: Pest pressure high | Oct: Pest pressure high | Nov: Pest pressure high | Dec: Building |
| Vine weevil grubs | Jan: Pest pressure high | Feb: Pest pressure high | Mar: Pest pressure high | Apr: Quiet | May: Quiet | Jun: Quiet | Jul: Building | Aug: Building | Sep: Pest pressure high | Oct: Pest pressure high | Nov: Pest pressure high | Dec: Pest pressure high |
| Release window | Jan: Quiet | Feb: Quiet | Mar: Quiet | Apr: Quiet | May: Release window | Jun: Release window | Jul: Release window | Aug: Release window | Sep: Release window | Oct: Quiet | Nov: Quiet | Dec: Quiet |
- Pest pressure high
- Building
- Release window
- Quiet
- Mealybugs (breed all year, slower in winter) · high pressure Mar–Nov
- Vine weevil grubs · high pressure Jan–Mar, Sep–Dec
- Release window · release May–Sep
Starter program
On a few pots, the swab and the repotting bench do most of the work. Releases are worth it only for a larger collection in a warm room or greenhouse, and there is nothing proven to release against the root-feeding mealybugs and aphids.
- ON BUYINGQuarantine and tip outKeep new plants apart for six weeks. Slide the plant out of its pot and look at the roots before it joins the others.
- FIRST MEALYBUGSRubbing alcohol on a cotton swab70% isopropyl or weaker (UC IPM). Test it on one part of the plant 1–2 days first, because some plants scorch. Repeat weekly.
- COLONIES PERSISTCryptolaemus montrouzieri5 beetles per infested plant, onto colonies with egg sacs, above 61 °F (16 °C).
- AUG–EARLY SEPHeterorhabditis bacteriophora250k–500k /m² of compost surface, watered in while the compost is moist and warm. RHS gives 54–68 °F (12–20 °C); UC IPM says at least 60 °F (16 °C), kept moist for two weeks.
Setting up indoors
Root pests are not seen until the plant is out of its pot, so make every repotting an inspection.
Check the roots of any plant failing without cause
Root mealybugs are generally not seen until the roots are exposed. Look for white wax on the roots.
Isolate root pests at once
UC IPM and UMass advise getting plants with root mealybugs out of the collection before the insects spread to neighbouring pots.
Use fresh compost, not garden soil
Clemson advises commercially prepared potting mix rather than soil from outdoors when repotting.
Water less than you think
Springtails in the pot are harmless, but Clemson calls them a sign of overwatering: let the compost dry between waterings.