Citrus mealybug
A soft, oval, 2.5–4 mm sap feeder dusted in white wax, with a fringe of short wax filaments round its edge. It is the mealybug most often found on houseplants. Colonies hide in leaf joints and sheaths, lay hundreds of eggs in cottony sacs, and coat the leaves below with honeydew and sooty mould. Indoors it breeds all year, out of reach of the natural enemies that keep mealybugs down outdoors, so a colony left alone keeps growing.
Adult females and cottony egg sacs of Planococcus citri in a leaf axil. Photo: pending.
Identification
Adult females are 2.5–4 mm long, oval and wingless, and look as if they have been rolled in flour. Round the edge runs a fringe of short wax filaments of even length — Koppert counts 18 pairs — with the two at the tail only slightly longer. Under the wax the body is light yellow to pink, and many show a darker stripe down the back.
The tail is the quickest way to separate the two common indoor species: longtailed mealybug has two tail threads longer than its body and gives birth to live young, so it makes no egg sacs. Citrus mealybug lays eggs in cottony sacs. Colonies sit in protected places — leaf joints, leaf undersides, stem tips, leaf sheaths.
Easily confused with
- Mealybug destroyer larvaeBeneficial — leave itLarvae grow to 1/2 inch (12 mm), over twice a mealybug's size, move faster and carry long wax filaments on top and sides, not just short ones round the edge.
- Long-tailed mealybugAlso a pestTwo tail filaments longer than its body; citrus mealybug has only short, equal-length filaments round its margin and often a dark stripe down its back.
- Cottony cushion scaleAlso a pestThe female carries a large white egg sac with fluted (ridged) sides; mealybugs have distinctly segmented bodies and older ones can still walk.
- Parasitised mealybugsBeneficial — leave itMummified mealybugs with emergence holes, or parasite pupae among the colony, mean parasitic wasps are already at work.
Damage symptoms
Mealybugs suck sap from the phloem, which weakens the plant, and excrete sticky honeydew on which black sooty mould grows. On a houseplant the mess — wax, egg sacs and a sticky shine on the leaves and the surface beneath — usually gives them away before any damage does. Early infestations are almost invisible, which is why they often seem to appear all at once.
- White cottony tufts in leaf joints, under leaves and at stem tips
- Sticky honeydew on the leaves below, later black sooty mould
- Yellowing, stunted or deformed leaves on heavily infested plants
- Leaf drop, and flowers or fruit that fall early
- Ants on the plant, collecting honeydew
Lifecycle & degree days
Females lay 100–200 or more eggs in a cottony sac, hatching into crawlers that wander, settle and cover themselves in wax. Outdoors mealybugs manage two to six generations a year, depending on species; in a heated room all stages are present all year. Development from egg to adult is slow compared with aphids or whitefly — one of the reasons a treatment has to be repeated for weeks rather than days.
- Lower threshold
- 8.5 °C (females; one lab study)
- Egg to adult
- ~667 degree-days above 8.5 °C (females; one lab study)
- Eggs per female
- 100–200+; up to 600 reported
- Generations / yr
- 2–6 outdoors (mealybugs generally); continuous indoors
Host crops
UC lists aglaonema, coleus, cactus, dracaena, ferns, ficus, hoya, jade, orchids, palms, philodendron, schefflera and poinsettia among houseplants that regularly carry mealybugs, and K-State adds chrysanthemum, croton, gerbera, pothos and marigold under glass. Outdoors UC lists it chiefly on citrus and several landscape shrubs, where natural enemies usually keep mealybugs below damaging levels. New plants are the usual way in.
Monitoring & action thresholds
No numeric threshold is published for houseplants. Outdoors, UC notes healthy plants tolerate low numbers; indoors there are no natural enemies to stop a colony growing, so act on the first one found.
Only winged males fly, so yellow sticky cards will not show an infestation — looking at the plant is the only way. Check new plants before they join the others, then inspect the plants that get mealybugs most on a regular round: leaf joints, leaf undersides, stem tips, leaf sheaths, and the pots, stakes and saucers where egg sacs are left. Ants walking up a stem are a reason to look closer.
Biological control
Biological control works on citrus mealybug in greenhouses and interiorscapes, but it is a program, not a single release. The mealybug destroyer Cryptolaemus montrouzieri needs warmth and plenty of egg sacs to breed on, so it belongs on an established colony. Green lacewing larvae work at lower temperatures (Koppert: average above 12 °C, against 16 °C for the beetle) and, in a study on another mealybug, preferred the youngest nymphs; in lab trials they often attacked mealybug destroyer larvae when the two were put together, though less when mealybugs were present as prey. The parasitoid Leptomastix dactylopii attacks citrus mealybug only. Keep ants off the plant or they will protect the colony.
Cultural controls
On a houseplant most of the work is physical, and none of it is a one-off: eggs are protected in their sacs and keep hatching, so whatever you do has to be repeated until no more crawlers appear.
- Inspect every new plant; if you cannot clean it, return or discard it
- Dab colonies with 70% or weaker isopropyl alcohol on a cotton bud, weekly until gone
- Hose sturdy plants with a forceful water spray, repeated every few days
- Hold back nitrogen fertiliser — soft growth raises egg production
- Throw out old, repeatedly infested plants rather than treating them again
- Keep ants off the plant; they guard mealybugs from their enemies
Chemical, last resort
- Insecticidal soapREI 12 h
- Horticultural oilREI 4 h
- Pyrethroids (bifenthrin; commercial label, highly toxic to bees and fish)REI 12 h
Sources
UC IPM Pest Notes: Mealybugs, Publication 74174 (M. L. Flint, 2016)
UC IPM Pest Notes: Aphids, Publication 7404 (M. L. Flint, 2013) — soaps and oils
K-State MF3001, Mealybug Management in Greenhouses and Interiorscapes (R. A. Cloyd, 2011)
Koppert, Citrus mealybug (Planococcus citri) pest profile (accessed 2026)
University of Minnesota Extension, Citrus mealybug (accessed 2026)
Satar & Karacaoğlu, Bioecological characteristics of Planococcus citri, Turkish J. Entomol. (2017)
Khan et al., Predatory potential of C. carnea and C. montrouzieri larvae, J. Insect Sci. (2012)
Golsteyn et al., Intraguild interactions between mealybug predators, Insects (2021)
Koppert Cryptobug and Chrysopa pages; Arbico Organics Mealybug Destroyer listing (accessed 2026)
Product labels: M-Pede (Gowan), SuffOil-X (BioWorks, US), Talstar Nursery Flowable (FMC, EPA 279-3155)
Page status
Drafted from the sources below, then checked claim by claim against those sources on 23 September 2026.
Suggest a correction →Citrus mealybug by crop
The same pest behaves differently on different hosts. Each page below gives the host-specific control, rate and threshold.