How many inches can a cricket be? One. Yes, a four-inch Oscar can eat most bugs. But be very cautious with the waste. The proteins and fats that don't get digested will foul the water in hours. You could scoop out the turd as soon as you see it.
Also, remember that on a live food regimen, once per day is plenty with your situation. Normally it would be twice per day, but in a ten gallon tank...you know.