Hi Greg,

It's hard to make a guess without photos or other information. Could you send photos of what you're seeing? Did the trees leaf out and they are now chewed? Are these fruiting pears or ornamental pears?

Hi again,

Honestly, I'm stumped. I sent you photos to three colleagues and none had any great ideas. One noticed that there is a perfect circle in one of the leaf, indicating leaf cutter bees (good guys!) but none of us had every seen that extensive of leaf consumption before.

Are there bits of leaves on the ground? Do you have wildlife in the area (squirrels, deer)? Any signs of insect frass? 

The fortunate thing is that pears form a lot of leaves, so losing these won't affect the overall health/growth of the tree. If it continues, please keep me posted.