Scale insects: how to spot, prevent and treat them pest

How do you spot scale insects?

Scale like bumps stuck to the stem and the underside of the leaves, on the indoor species preferably along the midrib. They do not move and are easy to overlook as part of the plant. The soft scales give off honeydew, so the leaves turn sticky and blacken with sooty mould. In a heavy attack the growth falters.

How do you prevent scale insects?

As with the mealybugs: the adult females do not fly, so they arrive with a new plant. Check the stems and the veins on the underside of the leaves and keep a new plant apart for a while. A healthy, well kept plant takes the odd scale and action is not always needed. Put a plant that may go outdoors in summer outside, because cooler air and the predators do more than spraying.

What works against scale insects?

An adult scale is protected from the spray under its waxy shield, so scrape it off with a fingernail, a cloth or an old toothbrush while there are few of them. A badly infested house plant is often better thrown away than treated.

Which plants get scale insects? 14

Fruit trees 7

Ornamentals 1

Houseplants 6