That looks like damage from an Avocado Lace bug. They insert their needle like mouth piece into the bottom part of the leaf. That entrance hole often allows fungi like anthracnose fungi to enter the leaf. Not much is known about how to combat them but Green Lacewings are believe to be a natural predator. You can use chemicals that attack sucking insects also. I would go natural and use Neem oil. Use 1 1/3T of neem oil, enough dish soap or natural soap to break up the Neem oil, I cup of H2O2 and a gal of warm water. Spraying once or twice a month in the early morning or afternoon would help you control the pest problem.