The native kidney spot ladybird, Chilocorus renipustulatus, specialises in feeding on scale insects and can naturally colonise infested plants reducing infestations.
The best time to control scale insects is when the more vulnerable newly hatched nymphs are present. As this insect has two generations a year, the best times for treatment are in June and early September. Dead scales often remain attached to the plant but new growth should stay clean if the treatment has been successful.
- Organic sprays, such as natural pyrethrum (e.g. Bug Clear Gun for Fruit & Veg, Ecofective Bug Killer), fatty acids (e.g. Solabiol Bug Free, Doff Greenfly & Blackfly Killer) or plant oils (e.g. Vitax Organic Pest & Disease Control, Bug Clear for Fruit and Veg) can give good control of scale insects. These pesticides have a very short persistence and so may require reapplication to keep scale insect nymphs in check. Plant oil and fatty acid products are less likely to affect larger insects such as ladybird adults
- More persistent insecticides include the synthetic pyrethroids lambda-cyhalothrin (e.g. Westland Resolva Pest Killer), deltamethrin (e.g. Provanto Ultimate Fruit & Vegetable Bug Killer) and cypermethrin (e.g. Py Bug Killer)
- The systemic neonicotinoid insecticide acetamiprid (e.g. Bug Clear Ultra) is also available
- Follow label instructions when using pesticides
- Inclusion of a pesticide product does not indicate a recommendation or endorsement by the RHS. It is a list of products currently available to the home gardener
- Do not spray near plants in flower due to the danger to pollinating insects
Pesticides for gardeners (Adobe Acrobat pdf document outlining pesticides available to gardeners)