In the end, I used a sleep sack that had little raglan sleeves and cut out a front and back panel (adding seam allowances and extending the bottom and making a little stinger shape) and two sleeves. When I say that I added seam allowances, I mean that I just cut the fabric a little outside the edge of the template...like, I did absolutely no measuring and it was lovely. For the yellow stripes, I just laid one of the body pieces on some yellow fleece and cut out a piece of yellow in the shape of the middle (tummy) part of the template. Then I cut the yellow piece into stripes and sewed down every other stripe.
I sewed the stripes on to the body pieces first. If I was going to do anything differently, it would be to sew the stripes onto the black fabric before cutting the body pieces out. The fleece stretched a bit when sewing and it took some time getting used to, so the stripes were not perfectly straight. This meant that when I sewed the two body pieces together, the stripes didn't completely match up. As I was sewing the side seams, I worried that this would look terrible, but in the end it is totally not a big deal (and I am usually way crazy about details like that). I slapped (literally, note that my seams are not sewn straight at all) seam binding on the wrists and the neckline, which was a joy since I now actually know how to sew the stuff on correctly thanks to this tutorial. The zipper was just stuck on after cutting the front body piece down the middle. Fleece doesn't fray, so I just cut and sewed and didn't fuss at all.
I also made a little hat with the help of this tutorial and then I wrapped pipe cleaners around the little ears. There is no photo because Bean woke up from her nap before I could set it all up, but trust me, it's cute. The pipe cleaners are very temporary, which is important because if I feel like Stella's grabbing at them, I'm just going to yank them off.
This came out way way better than I expected it to. There were really no bumps along the way and this is why I get myself into trouble. I proclaim that I cannot sew and then I stumble my way through a project and it looks half-decent and no one believes me. In truth, knowing that this was a project that would be worn once and that its sole purpose was to simply read as bee, I was really able to relax and omit stupid things like sewing little insect legs (yes, I considered this at one point) and not care if the shape wasn't perfect or the zipper wasn't straight or whatever. It reminded me of my metals class when my teacher encouraged me to just make something quickly for the sake of finishing it, rather than in an attempt to make the perfect piece. I think I stared at her blankly for a while and then got back to filing all of the edges of each of my handmade jump rings for the necklace chain I was making from scratch. But now I see the beauty in making something quickly and without the need for it to be perfect. Sometimes what you end up with will get the job done! Stella will be a bee! And pssst! I think it all cost under $10!