Using nematodes to get rid of scale insect
A bit about Scale Insect
There are 25 species of scale insect, they live on a wide range of plants inside and out. They are small but easy to identify, they tend to be 1mm to 1cm and look like little bumps on the back of leaves and stems.
They are a sap sucking insect so they secrete honeydew which makes the plant sticky and can cause sooty mould.
Chemicals sprays seldom work to control scale due to their anatomy. The 'scales' are their armour protecting them from sprays and many natural predators.
Nematodes
Nematodes, sprayed onto the plant foliage, swim underneath the scales killing them. It's a different type of application than you may be used to with nematodes, the temperature must be above 14°C for treatment to work so only treat if this can be achieved. Also the plant must be kept wet for at least 12 hours following application either by misting or covering.
It may take 3 treatments. Ideally, 3 times at 2 week intervals (with a 3 week gap between the 2nd and 3rd applications) but it might take less applications depending on how well the first application works.