Of course as a researcher who studies these things, Anna knew the answer to what had landed on her bubble butt already, and it arrived a while later with the drone of a large insect. Anna's head was still inside the plant and was bleary from poor sleep and a distinct lack of orgasms. She couldn't really see what was outside all that well as what little light she could see was diffuse and blurry through the leaves of the plant. The wing beats got louder and louder, until eventually Anna was sure it was right next to her. She startled at the sensation of multiple insect legs landing on her ass cheeks. The sensation was a surprise, but thankfully the ends of the legs weren't sharp and didn't cut into Anna at all. Based on how the plant moved when the insect landed it had to weigh around 5-10 pounds.
The insect moved around on her ass like it was looking for something. A light pressure of something warm and slimy against her pussy told Anna she was in for quite the experience. The plant had made sure to plug the other two holes so there weren't any accidents. The insect riding her ass was very particular about the environment for their brood after all and they had notoriously bad aim. The repellent Anna used during her time down in the jungle was enough to keep most breeding insects away that relied on swarming a humanoid and breeding them. It was cheap and effective and was a necessity when travelling in the 2nd layer of the dungeon. Like most adventurers she not only applied it to her armpits and neck, but also to her toilet paper after using the bathroom just in case she was incapacitated.
None of that matters after the plant had spent so much time washing the scent of her repellent away with it's slime and by fucking her holes clean. After some prodding and an almost-orgasm when it rubbed against her clit repeatedly, the insect found it's mark and it's ovipositor plunged into Anna's urethra. Almost immediately she could feel small orbs about the size of a large marble being pumped down the tube into her bladder massaging the underside of her clit. The ovipositor was a tight fit already and each of the eggs being forced into her were just slightly larger than the largest bump on the vine that had trained her. There was no way the ovipositor would have been able to fit in her urethra, much less it's eggs without the plant moulding her body to accept it for hours upon hours.