Which of the following is NOT a leaf-eater?

The Red Heart Beetle is not a leaf-eater, making it the correct answer in this context. This beetle specifically targets the wood of trees rather than their leaves. Its feeding habits typically involve boring into the inner tissues of trees, which can lead to damage in the structural integrity of the wood rather than affecting the foliage.

In contrast, the other options, such as the Gypsy Moth and Asian Gypsy Moth, are both well-known for their leaf-feeding habits. They are notorious pests that can defoliate trees, leading to significant ecological and economic impacts. The Pine Sawfly also primarily feeds on the needles of pine trees, contributing to their designation as leaf-eaters. Understanding the different feeding behaviors of these pests is crucial in managing forest health and mitigating damage to trees.