The insects within you alert you with subtle motion when near danger and fortify your body. Your dexterity score goes up by 2 and your constitution score goes up by 1.

Your lifespan is shortened by a few years and in some race's cases, a few centuries.

While flesh borers are uncaring of their host's alignment, the circumstances of infection and continual growth of the hive may alter the mentality of the host.

You have the same height as your old race before infection. As the years go on height may increase or decrease by an inch or two.

The flesh borers keep your walking speed average. Your base walking speed is 30 feet.

You have the same vision you had as your old, uninfected race.

The hive is self preserving, to the point of even altering your mental state. The instincts of the hive protect you best it can. You have advantage on saving throws against being charmed.

Common and one from your past, uninfected race options.

The hive alters the body, taking away past race-specific traits and ability score improvements. You have no traits or abilities from the past race you choose unless specified.

The hive needs time to maintain itself. You must perform light to no activity for 8 hours a day so the hive can work toward repairing you and tending to itself. This light activity may be reading a book, keeping watch, or sleeping. You do not need to sleep unless you wish to. These 8 hours count as a long rest for you.

As time goes on the hive begins to look after you, its host, repairing you from the inside. 

At level 5 you heal an additional 1d4 per hour when at rest. This changes to 1d6 at level 10, 1d12 at level 15, and 120d at level 20.

Heat increases the activity and metabolism of the hive. You are not affected by hot weather effects. Hot temperatures add an additional 2d6 to your rolls with the Symbiosis feature.

Your body needs to stay warm to keep the hive alive. If you body drops to low temperatures the hive cannot function properly and neither will you. You are vulnerable to frost damage. When your body is exposed to freezing conditions you walk 10ft slower than normal, cannot benefit from Symbiosis, and your Hive Swarm becomes a 5ft cone.

Your body holds hundreds of insects in various stages and you can summon them through your flesh to show themselves. If you display your bored flesh you have advantage on intimidation checks and disadvantage on persuasion checks for 10 minutes.

The hive learns the benefits of protecting the host verses devouring it. The host can, once per long rest, release a mass of swarming insects.

The swarm is a 20ft cone. All within the cone must make a dex save verses 8+ your dex bonus + your con bonus.

Those that succeed take half damage.

Those that fail take full damage and must roll a constitution saving roll to beat 8+ your con bonus + your proficiency bonus. On a failed roll they become infected.

Those that become infected take 2d4 acid damage each turn they are infected. At the end of each of their turns they must roll another constitution saving role against you. If they succeed they are no longer infected.

Swarm damage starts at 2d6 acid damage then changes to 3d6 at level 5, 4d6 at level 10, and 5d6 at level 15.