Winter aphids and mealybugs

   Winter is often rife with indoor pests; the natural predators, ladybird and hoverfly larvae that might find their way in through an open window in summer, are deep in winter slumber, and the central heating makes for boomtown for small suckers.

Mealybugs on a stem
Young mealybugs. Photograph: Gap
Aphids are familiar, tiny sap-sucking green insects, but mealybugs are easier to miss: they are rather good at pretending to be bits of fluff. That is until your whole plant is covered in fluff and turning pale.

When young mealybugs are orange they look much like other soft-scale insects, but the adults are wildly different. The males look like tiny, dark wasps and are frankly hard to spot; and the females produce a white, woolly meal to protect themselves and their eggs from drying out. You often find them in the axis of stems and leaf joints. They excrete a sticky substance that attracts sooty moulds (as the name suggests, the leaf looks as if it has been dusted in soot). At this point the plant really begins to suffer.

There are several solutions. Soap suds will asphyxiate the breathing holes of the insects, so wash plants down with diluted horticultural soft soap. You might find it easiest to take the plant to the bath to do this: you’ll need to get the solution into all the nooks and crannies. Be prepared to do it repeatedly; they are very good at hiding.