Mindworms are nasty

[Fugi the Great]

Don't forget to check out that city square that just changed to fungus. I just did, and lost a size 16 city in a single turn. It was defended by two 4-12-4 garrisons with Hypnotic Trance and a probe team. I had Neural Amplifer, and 20% Planet in my favor. The defenders took out at least six of the Demon boil mindworms before they blew up. Unfortunately there were at least 20+ more demon boils in that boilover that destroyed that city. Luckily there was't any secret projects in that city. I'll never forget to look again.

[Mauddib]

Sounds like your having Ecological Damage from high production bases. Reduce your production number, any base from around 73 and under will keep your Ecology Damage at Zero. Anything above that and you get the hoards, usually Locusts, from the Fungus.

Good defenses: Must have Neural Amplifier & Perimeter defense. Foils are not good defensive units. Infantry or HoverTanks are Ideal. In addition, if your going to have High production bases, better get Psi defense for your units.
I had a Hovertank--thats 1 tank--with Psi defense as armour with AAA abiltyand it withstood 15Locusts without even a scratch.
Hope this helps.

[Transcend]

The maximum mineral production per city depends on how many centauri preserves and
temple of planets are built. I had several cities with mineral production well over 100, and that before any temple of planets are built. I think you would no problem with cities over 200 mineral production, given enough temples of planet.
Once the governor decides to build genejack factory along robotic assembly plants, nano replicator, and quantum converter, that boosts the production over 300!!! The resulting ecological damage was about 370. Luckily, I found the mindworms and destroyed 40 of them! It was easy because they were stacked on two piles only.