wiki says that if you one-shot a fly, the others won't link. So you could try trying to one-shot them one at a time with your strongest nuke. At 75, I don't know if the gap in level is big enough between you and the flies to just outright nuke them down with a bunch of -gas before they kill you.
Lyonheart of Lakshmi
lvl 99 NIN WAR BST THF BLM SCH WHM
1/467 on signed HQ Weskit!!!