Our strategy for controlling avocado thrips is to release lacewing at the rate of 10,000 per acre every other week until the fruit is too large to be scarred (about 3/4 inch in length) beginning about four weeks before the flowers open.
Once the fruit starts to form, it is important to start checking for thrips on the fruit. If we find one or more thrips on a fruit we count it as infested. When 20% or 1 in 5 fruit are infested, we consider spraying with Veratran-D, Agrimek, or Success to avoid pest damage. Since none of these materials are very toxic to lacewings, we continue releasing them on schedule until the full effectiveness of the pesticide has been evaluated.
The decision on when to treat and what to treat with involves a number of issues. Below are links to more information which, we hope, will assist you in making the best decision for your particular situation.