How to Control the Scale on Lilac Bushes
- 1). Remove any heavily infested parts of the lilac bush. Bag what you remove and take it out of the garden.
- 2). Use a hard jet of water from the hose to wash off anything you see crawling on the lilac bush. These are the juvenile scale insects, known as "crawlers," that are active in late May to early June. You can also control them by spraying them with insecticidal soap. To be effective, the soap spray must completely cover the crawlers.
- 3). Spray the lilac bush with dormant oil in early spring. Follow the instructions on the product's label.
- 4). Release lady bugs near your lilac bush. Lady bugs, available at large gardening centers, will feast on the scale.