Our Pest Control Expert, Julian Ives, has spent many years advising commercial growers and gardeners on the subject of safe and efficient natural pest control treatments.

Here he shares his experience on the problems Scale Insects can cause in the garden and how to get the best from the biological control measures we supply... 

How to Use Soft Scale Killer
Apply Soft Scale Killer when soft scales are observed on plants. Soft scale killer is not recommended for use outdoors. The minute parasitic wasps contained in soft scale killer inject their egg into the soft scale insect. This kills the soft scale and leads to the production of a new Metaphycus parasite, which hatches from the scale insect. These tiny wasps need long days to reproduce in and a minimum temperature of 18.c. For indoor use this is normally from March-October. To apply Soft Scale Killer open the bottle near the infested plants and let the parasites fly to the scale insects. It is best to apply late in the day when vents and windows are shut. A guide to application rates is 3-5 Metaphycus per plant. Repeat treatments 2-3 times over 1-2 months.

Appearance and Lifecycle
Scale insects are often divided into two groups; soft scale and hard scale. The soft scale has their shell attached and with the hard scale shell it is not attached. Outdoors there are one to two generations per year but indoors there can be 3-6 with generations overlapping each other. Eggs are normally laid under the shells and newly hatched nymphs will crawl around plant surfaces spreading the infestation. There are up to 25 species of scale in the UK, most are between 1-10mm in size.

Symptoms and Damage
Scale insects feed on plant sap from plant leaves and stems. Soft scale species then secrete honeydew onto leaves. This is a sticky substance that often attracts fungi, which then turns black. Soft scale insects thrive best in warm, humid and shady conditions. Hard scale or armoured scale species don’t produce honeydew but do inject poisonous substances into the plant. This turns leaves yellow or brown. Heavy infestations of scale can result in poor growth and leaf drop.

Natural Choice Treatments
Biological control of scale insects is possible if the conditions are suitable for the predatory beetle and larvae and parasitic wasp used to control them. There are safe sprays such as Savona for controlling scale insects when the bioological control predators are at rest between October and March.