Texas FFA Nursery Landscape Practice Exam

Which of the following pests are difficult to control once they are under the bark surface?

1. Mealybugs

2. Aphids

3. Borers

4. Thrips

The correct answer is: Borers

Control of pests that reside beneath the bark surface of trees and plants can be particularly challenging due to their protection from both chemical treatments and natural predators. Borers, specifically, are a group of insects that tunnel into the wood of trees and shrubs as larvae, creating intricate galleries under the bark. Once they are beneath the surface, they are effectively shielded from insecticides and other treatment measures, making them very difficult to eradicate. In contrast, the other pests listed, such as mealybugs and aphids, typically infest the surface of plants or within the leaf axils and can often be managed through topical insecticides or horticultural oils. Thrips, while they can be pests, also do not generally hide beneath the bark as borers do; instead, they are more surface-oriented and often easier to control. The unique lifestyle of borers makes them particularly problematic for plant health, as they can cause significant damage to the vascular system of the host plant, leading to decline or death if not managed promptly.