How Can I Control Leafrollers?

Do you want to control leafrollers using the biological control method?

Do you want to control leafrollers using low-risk (organic) insecticides?

Do you want to control leafrollers using synthetic insecticides?

Several insects eat leafrollers including certain tachinid flies and ichneumonid wasps, which parasitize the larvae. After consuming the leafroller larvae, the braconid wasp forms a white cocoon next to the shriveled up worm inside its nest. A white cocoon is an indication that the parasite is present and might provide control. Lacewing larvae, assassin bugs, and certain beetles also are common predators. Birds sometimes feed on the larvae and pupae, although they usually prefer other insects.

The microbial insecticide Bacillus thuringiensis, which is sold as a variety of products, is effective against the larval stages of leafrollers. Bt is most effective on leafroller larvae when they are small (less than 1/2 inch long) and usually requires more than one application. Caterpillars must ingest the pesticide to be killed. Bt is available for use on ornamental trees, vines, and some fruit and nut trees.

Using synthetic pesticides is not usually recommended to control leafrollers. Because caterpillars must ingest the pesticide to be killed these sprays are not very effective against leafrollers who hide inside their cocoons of rolled leaves. These high-risk chemicals do present a threat to several beneficial insects so the use of low-risk, organic pesticides is advised. Insecticidal oil sprays applied in dormancy for scales and other insects will help control leafroller eggs on fruit trees.

You can easily cut the few damaged leaves from your plant and toss the caterpillars into a bucket of soapy water. Carefully pick through infested plants and those nearby to ensure you’ve gotten all the caterpillars, and check back weekly. Leafrollers don’t hatch all at once, especially if more than one species is present.