Answer: The leaf cutter bees really are an important part of our ecosystem and the half-moon shapes they cut from leaves won't harm your plants. What you describe on your Chinese lilac bush could be signs of drought, leaf miner damage, or if the leaves begin to turn black, a disease called lilac leaf blight. Leaf miners are tiny little wormlike critters that munch on the tissues between the upper and lower leaf surfaces. Eventually these parts of the leaves turn brown and the tips of the leaves begin to curl and turn brown. Look for off-color tunnels in the affected leaves. If you find none, then the curling is either from a droughty situation or a need for nutrients. Since it's late in the growing season, I'd just rake up the fallen leaves and next spring feed the lilac with an all purpose garden fertilizer (according to label directions).
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