Ehh, not so much for me. I appreciate that it didn't lay it out baldly in the end, but it felt like it waited a little too long regardless. As soon as he lied to his wife about what he saw outside, I started to wonder what on Earth motivated his actions. As soon as he started to climb without calling the cops first, I figured it out. There was a little bit too much attempt to make it "horrific" with the goofy leg-tearing thing; I was mentally tapping my foot, wondering how long he'd drag it out.
Still, it was cute. If I'd read it, I'd have liked it a lot more; I'd have been able to speed up my reading and not have had to wait so "long" for it to finish up where it was clearly going. I like the image of ants striving boldly to save their entire hill by climbing to the tops of grass stalks and vines, hallucinating some terrible ant-threat. (Though I spent a fair amount of time thinking that, really, you'd probably just have most higher functions shut down and be kind of clumsily lurching around on pure lizard-brain with a need for height. Cordyceps is creepy, but fungi aren't known for their predilection toward ironic twists.)