While I'm all for feeding live insects to fish, in this case, I wouldn't. Fish food contains a lot of oils that can go rancid if the food is old and stored improperly, and if there are bugs in it, then it's likely rancid. So no, I wouldn't feed it to the fish.
Fish food keeps for a long time, but anything older than three months I'd dispose of. I feed a variety of foods, but dried staple foods I'll have 3-4 small tubs in the rotation, along with feeding live and frozen, so even with 4 tanks I wouldn't get a huge tub of food since most of it is likely to wind up wasted.
So yes, sorry, sounds like the food is off, so I wouldn't risk it with the fish.