by arthur_dayne, Nov 22,2011
I made some changes here that would make this more of a "bug" world than an "insect" world, i.e., making Spiders the green tribe (seems obvious now, in hindsight). I've also added some less prevalent bug-types by color. --Greg
Color tribes:
White: Bees, Grasshoppers (lots of grass in Plains, right?)
Blue: Flies, Water-bugs, Crabs?
Black: Beetles, Roaches, Mosquitoes/Ticks (Vampires of the bug world), Worms
Red: Ants, Centipedes, Dragonflies
Green: Spiders, Caterpillars, Mantis, Hornets?

Mechanics and Keywords:
Swarm: Not sure exactly what this would do yet. It would probably count the number of creatures under your control for some sort of effect. Could be tribal or not.
Army Ants
Creature - Ant Berserker
Swarm - If you control 3 or more ants, Army Ants gets +2/+2 and must attack each turn if able.
(Army Ants is an example of Swarm as a tribal mechanic)
Worker Bee
Creature - Bee Soldier
Swarm - If you control 3 or more creatures, Worker Bee has vigilance.
(Worker Bee is an example of Swarm as a mechanic that does NOT care about creature type, just about having lots of creatures)

Some ideas for insect mechanics:
Cocoon - This could be a mechanic similar to suspend where you can cast a creature for a cheaper cost with counters on it, but this version would have it in play, but it is arrested until the counters come off. Maybe instead of it being arrested, it could just be an 0/1 with defender while it has counters on it, but becomes the printed creature once all counters are removed.
Giant Moth :3m::W::W:
Creature - Insect
Cocoon 3 - :1m::W: (You may cast Giant Moth for its cocoon cost instead of paying for its mana cost. If you do it enters the battlefield with 3 metamorphosis counters on it. As long as Giant Moth has a metamorphosis counter on it, it is 0/1 with defender.)
During your upkeep remove a metamorphosis counter from Giant Moth.

Maybe a little wordy, but hopefully it can be cleaned up.
Burrow - A lot of insects live underground, so it is only fitting to have a mechanic for it. This could be something along the lines of a slide mechanic.
Tunnel Worm :2m::B::B:
Creature - Worm
B:: Burrow Tunnel Worm. (Exile this creature. Return it to the battlefield under its owner's control at the beginning of the next end step.)

This might be better as returning at the beginning of the controller's next upkeep as to make it a little less broken.
Carrion counters - This is the idea that bugs often find food from other dead animals including other insects. Basically I think a theme of creatures that gather food for the colony from the corpses of dead friends a foes would be cool.
Ant Gatherer :3m::R:
Creature - Insect
Whenever another creature dies, you may tap Ant Gatherer to put a carrion counter on itself.
Remove a carrion counter: Target creature gains double strike until end of turn.

Maybe double strike was a little much, just trying to think of red abilities that wouldn't just be lame (i.e. haste, first strike).

[[Magic: East West Draft Cast Custom Set/Flavor Discussion | Flavor Discussion]]

For Inspiration:

Chitin I, an old micro-wargame in which different types of insects battled over the harvest of a planet. Boardgamegeek Link