When a fungal pop happens, often it will produce worms, or their variants. So here are the probably-much-wondered-about rules about how many worms you get:
-On the first 6 pops for any given faction, and after the Voice of Planet is built, there are no worms, and also no contribution to ecodamage.
-Starting with the 7th pop for the faction, worms are generated in 2 stages:
-Stage 1 generates 1 worm for the pop square and each fungus-bearing square around it, except that:
1. On the 7th pop the squares northwest and north of the pop don't get worms, and on the 8th pop the square directly north doesn't get worms.
2. If the square has bases or units, it doesn't get worms.
3. If the closest base to the square has a different owner than the base generating the pop, it doesn't get worms.
-The type of these worms (worm, isle, locusts, or spore launcher) is determined as follows:
-If it is a land square, and the popping base's owner has at least one base on that continent, it will be worms with 80% probability or a spore launcher with 20% probability. (In SMAC vanilla, or if spore launchers have been disabled in alphax.txt, it's always worms.)
-If it is a land square, and the popping base's owner has no bases on that continent, it will be locusts.
-If it is a sea square, it will be an isle of the deep, unless the number of isles and locusts (together) already generated in this stage is a multiple of 3, in which case it will be locusts.
-The number of isles and locusts (together) generated in stage 1 is capped at the owner's total bases divided by 6, or the number pop this is for that faction divided by 3 (i.e. if it's the 12th pop for this faction, it's capped at 4), whichever is less. Any that would be produced beyond this are simply ignored. (Worms and launchers are not affected by this cap.)
-Stage 2 generates the rest of the worms in the pop square itself. It produces enough that the total (between both stages) is the number pop for the faction divided by 3, or the popping base's population, whichever is less. (If it's already over from stage 1, it doesn't produce any more but those that were produced in stage 1 are still there.) The type of stage 2 worms is determined similarly to stage 1 worms, except that if it's a sea square they will be either all isles of the deep (if the faction has at least 1 base in that sea) or all locusts (if it doesn't).
-If the pop is on a land square, there is a 25% chance to produce a fungal tower there as well.