What was the largest flying insectoid pollinator?

Megachile pluto is a large resin bee whose body length may reach 38 mm and a wingspan of 63.5 mm. But that’s nothing compared to the prehistoric and extinct Meganisoptera including the Meganeura, which had ‘dragonflies’ whose wingspan exceeded 70 centimeters! ?

There are "recent studies" linking animal gigantism in the Paleolithic to the increased atmospheric oxygen content.

Considering the size of some prehistoric insects I can’t help but wonder: how big was the world’s biggest insect(oid?) flying pollinator? ?