Scale insects are brown wart-like creatures that tend to congregate on the underside of leaves and suck sap. They are most visible when on a light-coloured area and on dark branches may be hard to spot. Scale insects are not easy to remove or to kill.The scale forms a kind of shell over the insect and protects it from predators and insecticides. The scales are not only unsightly - over a period of time they debilitate the plant and can even kill it.
Like all insects which pierce the cells, scale often leaves a tell-tale sticky residue which attracts black mould
Click here for Scale Predators
You will find different kinds of scale on different plants. The photo above shows soft scale under the microscope, the pictures below show scale on an olive and a bay, and the picture to the bottom right shows an unusual form of scale found on citrus called cotton cushion scale.
The adults are like a big maternity ward - they lay eggs underneath themselves from which hatch out literally hundreds of babies. So try and remove every adult you can with a fingernail, cotton bud, or soapy water.
The problem with scale (and mealybug) is that they spread through the tiny, tiny, crawling 'babies' (properly called 'larvae') who are only active for a short while and are very difficult to spot. For that reason it is good to wipe down your plants with horticultural soft soap or SB Invigorator if you bring in plants in the Autumn - a house or greenhouse is a great refuge for these troublesome pests.
We offer a control for soft scale, which is a mix of two different parasites: Metaphycus
helvolus and Encyrtus infelix. These are all very small flying insects which target
scale insects, sucking the juices out of some and laying their eggs in others. They
each live about a month and lay approximately 6 eggs a day, the young of which emerge
through a small hole after 3 or 4 weeks.