Mealybug Identification
Overview
Mealybugs are sap-feeding insects covered in a white, waxy protective coating.
They frequently hide deep within plant canopies, around stem joints and beneath leaves, so infestations may become established before they are noticed.
Typical appearance
Adult female mealybugs are usually:
- oval and soft-bodied
- white, cream or pale grey
- covered in powdery or filamentous wax
- slow moving
- approximately 2–5 mm long
- found in sheltered plant areas
Some species produce longer wax filaments around the edge of the body.
Common signs
Look for:
- white waxy insects
- cotton-like egg masses
- sticky honeydew
- black sooty mould
- white wax deposits
- ants feeding on honeydew
- colonies around stems and leaf joints
- reduced plant vigour
Where to inspect
Inspect carefully:
- leaf axils
- stem junctions
- beneath leaves
- around flower stems
- beneath loose bark
- around fruit clusters
- inside dense plant canopies
- around pot rims and drainage holes
Newly arrived plants and stock plants should receive particular attention.
Mealybug life stages
Crawlers
Young mealybugs, known as crawlers, are:
- small
- mobile
- lightly waxed
- responsible for much of the spread within a crop
Crawler stages are often more exposed and easier for biological control agents to attack.
Adult females
Adult females:
- remain wingless
- become increasingly wax-covered
- feed continuously on plant sap
- may produce cottony egg masses
Males
Adult males are small, winged and short-lived.
They are rarely responsible for plant damage and may be overlooked during crop inspection.
Mealybug or scale insect?
| Feature | Mealybug | Scale insect |
|---|---|---|
| Movement | Often moves slowly | Adults usually fixed |
| Wax | Powdery or filamentous | Shell-like or soft scale |
| Body shape | Oval and segmented | Often dome-shaped or flattened |
| Honeydew | Common | Common in soft scales |
| Main locations | Axils, stems and hidden canopy | Stems, leaves and woody tissue |
Mealybug or whitefly?
| Feature | Mealybug | Whitefly |
|---|---|---|
| Adult appearance | White waxy, oval insect | Tiny white moth-like insect |
| Movement | Crawls slowly | Flies when disturbed |
| Main location | Stem joints and sheltered canopy | Leaf undersides |
| Wax deposits | Common | Usually absent |
| Cottony masses | Common | Absent |
Mealybug or woolly aphid?
Woolly aphids may also appear white and waxy.
Useful differences include:
- woolly aphids often form colonies on woody stems or roots
- aphids have a more recognisable pear-shaped body
- mealybugs are usually oval and distinctly segmented
- mealybugs commonly hide in plant joints and dense canopy
Root mealybug
Root mealybugs live around roots and within growing media.
Typical warning signs include:
- white wax around roots
- wax deposits around drainage holes
- unexplained wilting
- poor root development
- weak growth despite adequate irrigation
Confirmation checklist
Mealybug is strongly indicated where several of these occur together:
- white waxy insects
- cotton-like egg masses
- honeydew
- sooty mould
- slow-moving colonies
- infestations hidden within stem joints
- ants visiting affected plants
- repeated outbreaks on long-season crops