As a developer, the only times I am bored with the work are when there is nothing that I feel I can contribute or there is no sense of ownership in the work. If you are just assigning your developer tasks all the time, as a developer it starts to feel like you're a computer mouse, being dragged from place to place. It's kind of debilitating because there's a lot of potential and developers have some insight on angles for creative direction that may not be taken into consideration. If there's nothing of value we can contribute, there's no heart in the work.

Give him some opportunities to pitch some ideas, contribute, or find ways to let the developer be invested in the work. If that is not possible, maybe give him some leeway to do some personal projects or side projects for the company.