Boxwood Psyllid is a very frustrating and common pest of all cultivars of Boxwood. While there are many things that cause more severe damage the appearance of the cupped leaves caused by the Psyllid drives me crazy. American Boxwood, Buxus sempervirens is the most susceptible. Psyllid over-winters as a tiny, orange egg that has been deposited in the bud scales. In Spring the eggs hatch when the buds of the Boxwood open up and the nymphs begin to feed right away. By early June you will start to see the winged adults hovering over your plants. During the summer, after mating is when the eggs are actually deposited into the leaves between the bud scales.
The nymph stage is what damages the host plant by feeding on newly developing foliage, causing the leaves to become cupped. This cupping conceals the psyllid, and provides protection while feeding. Damage to the host plant is purely aesthetic. Treatment should take place now to catch the nymphs before the start to feed. Talk to your local extension agent about what you should treat with. I have had great succes with Talstar.