You've got a carpenter bee or two which become very active in the spring. These bees are quite large and resemble a bumble bee. The males commonly do what you're describing and though they'll fly at you when you move close, they can't sting since they don't have a stinger! Females do have stingers so stay away from any that are in the flowers or in a nest. Carpenter bee nests will be found in wood, usually on the bottom side (the side facing the ground) and their holes will bore for several feet into wood if left untreated. Since they can cause a lot of damage, it's best to kill off nesting ones now using the DRIONE and spray with some CYPERMETHRIN to stop new ones from creating a nest. More information about this process can be found on line in our carpenter bee control article.