Rampaging Growth

Search your library for a basic land card, put it onto the battlefield, then shuffle. Until end of turn, that land becomes a 4/3 Insect creature with reach and haste. It's still a land.

Zask, Skittering Swarmlord

You may play lands and cast Insect spells from your graveyard.
Whenever another Insect you control dies, put it on the bottom of its owner's library, then mill two cards. (Put the top two cards of your library into your graveyard.)
{1}{B/G}: Target Insect gets +1/+0 and gains deathtouch until end of turn. ({B/G} can be paid with either {B} or {G}.)

Quarry Beetle

When Quarry Beetle enters, you may return target land card from your graveyard to the battlefield.

Caustic Caterpillar

{1}{G}, Sacrifice Caustic Caterpillar: Destroy target artifact or enchantment.

Ironshell Beetle

When Ironshell Beetle enters, put a +1/+1 counter on target creature.

Hunter's Edge

Put a +1/+1 counter on target creature you control. Then that creature deals damage equal to its power to target creature you don't control.

Insects

Giant Caterpillar

{G}, Sacrifice Giant Caterpillar: Create a 1/1 green Insect creature token with flying named Butterfly at the beginning of the next end step.

Thriving Grove

Thriving Grove enters tapped. As it enters, choose a color other than green.
{T}: Add {G} or one mana of the chosen color.

Crawling Sensation

At the beginning of your upkeep, you may mill two cards. (You may put the top two cards of your library into your graveyard.)
Whenever one or more land cards are put into your graveyard from anywhere for the first time each turn, create a 1/1 green Insect creature token.

Nantuko Cultivator

When Nantuko Cultivator enters, you may discard any number of land cards. Put that many +1/+1 counters on Nantuko Cultivator and draw that many cards.

Kraul Warrior

{5}{G}: Kraul Warrior gets +3/+3 until end of turn.

Giant Ladybug

Reach
When Giant Ladybug enters, you may search your library for a basic land card, reveal it, then shuffle and put that card on top.

Forest

Relentless Pursuit

Reveal the top four cards of your library. You may put a creature card and/or a land card from among them into your hand. Put the rest into your graveyard.