White bugs on plants

Several unrelated things get called white bugs, and they need different responses. Tap the plant first: if a cloud of tiny white insects flies up and settles back, it is whitefly. If nothing flies, look at what stays put: mealybugs and scales barely move, and springtails on the compost jump but rarely harm plants.

1. Greenhouse whiteflyTrialeurodes vaporariorumMost likelyFlies up in a cloud when the plant is disturbed, then settles back on the leaf undersides; females lay their eggs on the new growth. Wings held flat over the back, meeting in the middle. The flat, scale-like older nymphs sit still under the lower leaves.Full pest profile →
2. Citrus mealybugPlanococcus citriAlso commonFluffy white wax in small clusters in leaf axils, leaf sheaths and other crevices. Under the wax are oval, segmented bodies. Older nymphs and adults move slowly and not far, so a blob that seems to stay put can still be a mealybug.Full pest profile →
3. SpringtailsCollembolaAlso commonHarmlessOn the compost surface rather than the leaves, and they jump rather than fly. They feed on decaying plant matter, fungi and algae and rarely harm plants, though some species chew seedlings. Let the compost dry between waterings.Full pest profile →
4. Silverleaf whiteflyBemisia tabaciAlso commonThe same cloud, but the adults are smaller and yellower and hold their wings tilted like a roof, with a small gap along the back. Worth telling apart because it spreads tomato yellow leaf curl virus and several bean and cucurbit viruses.Full pest profile →
5. Brown soft scaleCoccus hesperidumLess oftenFlat, oval, pale yellow to brown bumps close to the midrib and main veins on leaf undersides, and on stems. Not white, but they leave large amounts of sticky honeydew and black sooty mould.Full pest profile →
6. Woolly apple aphidEriosoma lanigerumLess oftenOutdoors on apple, cotoneaster and pyracantha: fluffy white wax on the bark, round old pruning cuts and on young shoots, hiding a colony of dark aphids rather than mealybugs.Full pest profile →