My design for a sex bug, the Broodfly(I spent like 30 minutes on it so don’t eviscerate me pls)
The broodfly is on average the size of a small dog, but they never stop growing. A broodfly has an insatiable need for sex, as they die after a couple weeks without breeding a new female human. Because of this, they will leave their mates as soon as their clutch is born. Their ovipositor grows to about 8 inches long when hard, and they make their tip balloon to be entirely unremovable while hard. The mouth of a broodfly produces strong and sticky webbing that they can spat in large globs, encasing their prey, or in precise long strands that can cocoon those they target. They bite their mates, injecting Broodfly Saliva that has many perverse and permanent effects, including: a massive need for sex, increased sexual stamina, enlarged breasts, lactation, and causing the nipples to grow and become stretchy, allowing them to be penetrated like a sexual oriface. Broodflies lay 8-12 eggs in an hostess at a time and their larvae are born after about a week. The larvae then travel to their mothers breasts and penetrate the nipple, taking the time to slowly wriggle their way into their mothers breasts and feed off her milk until they emerge as a full grown broodfly 3-5 days later. Newly matured broodflies practice sex on their mothers, often pumping her full with a few eggs before flying off to find a new hostess, continuing the life cycle in another human woman.