In small numbers, leaf rollers are a minor pest to an otherwise healthy plant. If there are just a couple of the insects in your garden, there's no need to do anything. Leaf rollers can become a threat when they band together and attack a plant in large numbers over two or more growing seasons, however. Leaf roller damage is most visible in late spring when the young larvae devour the leaves, causing an unsightly skeleton of foliage. In early summer, larvae spin silky webs around young leaves to form a cocoon.
Over several weeks the larvae develop into moths that will lay eggs and set the stage for a leaf roller infestation the following year. Leaf rollers are most vulnerable in late spring before they form their silky cocoons. Spray your plants with Bt (Bacillus thuringiensis)-a biological insecticide produced from bacteria. You also can control leaf rollers with a dormant oil spray applied in early spring just before buds open. The oil, available at garden centers, will prevent the eggs from hatching.