Blueberries [all varieties] are commonly infested with
thrips, scale insects, mites and maggots.
Some Rabbonim seem not to be aware of the facts and the seriousness of this issue and issued some misleading information.
Different seasons & different localities will harbor some or all of the above insects.
Wild and organic blueberries are the most infested.
Washing may get rid of some but not necessarily all of the insects.
Some of the areas that are more heavily infested include, New Jersey, California, Mexico, Canada, the Carolinas, Texas, Florida, Georgia, Maine, etc
Therefore all Blueberries, all seasons, all locals should not be used unless they were checked by trained experts in these insects.
The above includes, fresh, frozen, dried, filling, jams, etc