Scoop out balls of melon using a melon baller or cookie scoop. Use different sized scoops, if desired, to achieve different-sized balls of melon. Transfer the melon balls into a large mixing bowl.
Cut off the scooped part of the melon and repeat the process, scooping and cutting until all of the melons have been balled.
Add the blueberries to the mixing bowl with the melon balls.
Combine the lemon juice and syrup to make a dressing, then pour it over the fruit.
Let the dressing soak into the salad for at least 5 minutes.