Trees which have a dense canopy and vigorous shoot growth tend to support greater populations of caterpillars.
- If shoot growth then ceases when caterpillars are young due to water stress and/or a heavy fruit load, the caterpillars tend to move to feed on fruits, especially those in clusters, and damage intensifies.
- Avoiding this situation by tree management reduced losses.
- Furnishing the trees with artificial refuges for earwigs and other insect predators (see Rosy apple aphid) is likely to help reduce young caterpillar populations.