That's normal comes with the substrate. When you change the substrate out, bake the new stuff at 200-250 for 3-4 hours or you can boil it. It will keep the bugs away for a long time, but not usually forever.
The bugs might actually be beneficial. They feast on your tortoise’s leftovers, mold, and maybe his poop.
Please keep in mind that your tortoise is an adult that needs a minimum enclosure size of 8x4 feet. If your profile picture is his current enclosure, you need to make changes ASAP.