One of the principal reasons we practice integrated pest management when caring for trees and shrubs is to reduce our use of pesticides, thereby conserving natural predators and parasitoids of insect pests, allowing mother-nature to take care of the pest problem. These predators and parasitoids don’t always solve the problem and sometimes we have to intervene, but they will oft times do a great job of cleaning things up.
The above pictured predator is a larva, or maggot, of a syrphid fly, and it’s feeding on wooly beech aphids found yesterday on a European, or copper, beech in New Canaan, Connecticut. The adults are known as hover flies or flower flies. Hover fly adults have no defense against being predated themselves but in the never ending panoply of fascinating insect behavior adults of some species of hover flies change color to ward off predators, and still other species of hover flies mimic insects like honey bees or wasps that do have special defenses against predators.
This link, from my friend and mentor Dr. Michael Raupp at the University of Maryland, has more information and some great video of these prolific predators.