How many bees did you find dead? Honey bees are very sensitive to pesticides, be *very very* careful using them around your bee hives. From what I've read (I've never experienced it and hopefully won't) a large number of bees out in front of the hive *usually* signify pesticide poisoning. Bees are going to die naturally so a few bees dead aren't to be worried over.
Cinnamon is good for discouraging some ants, it doesn't always work but in lots of situations it seems to. I sprinkle it around the base of the hive stands (cement blocks in my case), around the base of the bottom boards where they sit on the blocks, underneath the hive on the ground and finally on top of the inner cover. Very soapy water can be mixed up (cheap dish-washing or car-washing soap) can be sprayed on ants on the ground and poured onto individual mounds...it is a good ant-killer. Soapy water will kill bees, too, so be careful with it, but most of the time the bees will not be on the ground where you're spraying. The soapy water isn't isn't airborne like an aerosol spray can be, the soapy water will pretty much go where it's sprayed and not drift in the air.
SHB....don't leave lots of empty space in your hives and keep your hives in FULL SUN. Does your hives get plenty of sunshine? Keep plenty of in-hive traps (such as your beetle blasters) in the hive. I mix apple cider vinegar, mashed up over-ripe banana, and vegetable or mineral oil in a 16oz plastic drink bottle. I let it sit for a couple of days, walking by and shaking it hard every so often to get everything mixed the best I can. I use this in my Beetle Jail Jrs and they seem to catch a good many beetles. Restricting the beetles ability to enter the hive by sealing the top off with window screen over the vent/feed holes and possibly reducing the front entrance will give the bees less of an area to have to guard. Oil trays beneath a screened bottom board appears to catch many beetles.
Keep an eye on your colonies. If they have been weakened by something then you have a third enemy to beware of...wax moths. Be on guard.