Kansas Turf Pest Control 3B Practice Test

Aphids damage trees primarily by sucking sap from the plant's phloem. They use specialized mouthparts to pierce the plant tissue and withdraw the sugary sap, which deprives the tree of nutrients it needs to grow and stay healthy. This sap removal can slow growth, cause leaves to curl or yellow, and weaken twigs and shoots. A secondary effect is the honeydew they excrete, which coats leaves and can lead to sooty mold and attract other pests. The other options don’t fit as well because chewing leaves is done by insects like caterpillars and beetles, not aphids; attacking roots is a behavior of some other pests, and while root-feeding aphids exist, the typical and most visible damage from aphids is sap-sucking on above-ground parts. Aphids don’t produce toxins that poison the plant; their impact comes from feeding and the resulting nutrient loss and mold growth on honeydew.