Most likely. Carpenter bee holes are used as nests where eggs are deposited. If you don't treat with the Drione we have listed in our Carpenter Bee Control article the eggs won't die. In fact, they'll hatch out the following year attempting to complete the life cycle of the bees. What you saw was most likely the carpenter bee larvae. At this point I would make sure any holes still remaining in the wood are properly treated or else the swing set will suffer more damage. And if you notice adult bees hanging around this spring, be sure to spray with the Cypermethrin to stop them from boring new holes.

Most any carpenter bee would be attracted to something like a cedar swing set. Any time you've got a lot of wood with some big beams in close proximity to one another, carpenter bees will naturally be curious. This is prime nesting grounds for them and in the spring, that's all they're doing. Fortunately, they aren't too aggressive. That being said, I would keep the kids away for now and at least till you've treated and the activity diminishes. If you are seeing any holes in the lumber, treat them with the DRIONE as described in our carpenter bee control article. If the bees are only hanging around and don't seem to have any nests drilled yet, spray everything down with the Cypermethrin. This will force them to move away as the cypermethrin will repel them since they don't like it. Both these products are safe to use on the swing set; you just need to keep the kids away during the treatment as explained in our product safety section.