Greenhouse Thrips in avocado has not been a major issue for many years, not since the days of malathion sprays that invariably brought on more pests than it seemed to treat. Recently, we've seen an increase in greenhouse thrips damage, this along with stink bug, false chinch bug and seed weevil and whitefly in citrus
https://ucanr.edu/blog/topics-subtropics/article/tis-season-some-reason-find-different-pests
Greenhouse thrips like a greenhouse environment and when it can't find a greenhouse, in the field it will look for a cluster of avocado fruit that will help maintain a given temperature.
In that special harbor it will feed on the fruit, causing a bronzing, which devalues the fruit
In the old days, growers would spray malathion on the affected trees, leaving as much of the orchard unsprayed to maintain beneficials. They would also release a small parasitic wasp, Thripobius semiluteus , that would help control the insect. Also, they would size pick in order to reduce cluster size or do a strip pick to remove the attractive fruit all together.
Something in the weather and environment has brought this insect back to the avocado orchards along with some of these other visitors we haven't seen in a while.
For more information on greenhouse thirps (both singular and plural thrips has an "S"), read on: https://ipm.ucanr.edu/agriculture/avocado/greenhouse-thrips/#gsc.tab=0
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