Which of the following is a type of tree insect pest with chewing mouth parts?

Caterpillars are classified as tree insect pests with chewing mouthparts, which distinguishes them from other options presented. Their primary feeding mechanism involves chewing, allowing them to consume leaves and other plant material. This feeding can lead to significant damage to trees and plants, particularly during the larval stage, when their growth requires substantial amounts of foliage.

In contrast, aphids and scales are examples of pests that possess piercing-sucking mouthparts, which they use to extract sap from plants. Leafhoppers also use a piercing-sucking method to feed on plant fluids, which can cause stress to the host plant but does not result in the kind of leaf defoliation typical of caterpillars. Understanding these different feeding methods is crucial for proper pest identification and management strategies in arboriculture.