Which insect is known for leaving honeydew or sooty mold on leaf surfaces?

The correct answer identifies aphids as the insect responsible for leaving honeydew or sooty mold on leaf surfaces. Aphids are small, soft-bodied insects that feed on plant sap. As they feed, they excrete a sticky substance known as honeydew. This honeydew can encourage the growth of sooty mold, a dark fungus that coats the leaves and can obstruct sunlight, thereby affecting photosynthesis and overall plant health.

Understanding aphids' role in this context is critical for pest management in right-of-way settings, as their populations can quickly grow and lead to significant harm to vegetation. Proper identification and management can help mitigate damages caused by their feeding and the associated secondary problems from the mold they promote.

The other options do not produce honeydew in the same way that aphids do. Grasshoppers primarily consume plant matter without producing significant quantities of excrement that would lead to honeydew. Ants do not excrete honeydew; rather, they are often found tending to aphid colonies because they feed on the honeydew produced by these insects. Beetles, while they may also infest plants, do not typically produce honeydew or sooty mold in the way that aphids do.