Where do woolly aphid infestations often begin aggregating, suggesting an exploitation of plant weakness?

Near pruning wounds or areas caused by broken branches

Woolly Apple Aphids display a tendency to locate and exploit existing weaknesses in the host plant's structure, which serves as an entry point into the tree's vital sap-transporting systems. Specifically, colonies frequently initiate or become heavily concentrated around areas where the tree has previously suffered mechanical injury. This includes points where branches have been pruned or where bark has been broken or damaged. These areas of recent wounding or ongoing healing represent compromised points in the tree's physical defenses. By settling near these tissues, the aphids gain easier access to the phloem sap flow that these developing tissues require, allowing them to establish feeding aggregations that may eventually cause localized swelling or gall formation.