What are mealybugs?

Mealybugs are soft-bodied, 4mm-long insects often found on greenhouse plants and house plants such as cacti and succulents, feeding on their sap. They're covered by a white, waxy secretion, and congregate in leaf axils and other inaccessible parts of plants. In large numbers they can debilitate the plants and secrete a sticky, sugary honeydew that covers the leaves, which often results in further problems, such as sooty moulds.

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Symptoms

Mealybugs and their white secretion on leaves
Mealybugs and their white secretion on leaves

Infestations of white, waxy insects on indoor and greenhouse plants, along with sticky honeydew and possibly sooty mould on the leaves.

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How to control mealybugs

  1. Inspect new plants before buying them or bringing them indoors
  2. Move hardy plants outside where birds such as blue tits can control them naturally
  3. Dispose of fallen leaves that might have the bugs or eggs attached
  4. On plants like cactus and succulents you may be able to remove mealybugs with tweezers, if the infestation is small
  5. If mealybugs are present in large numbers, a natural way to kill mealybugs is to use the predatory ladybird Cryptolaemus montrouzieri. Do this in summer when temperatures rise
  6. Alternatively try spraying plants with fatty acids or plant oils. You may need to do this a few times to completely kill the mealybugs
  7. Severely affected plants may need to be destroyed
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