Devouring Swarm

Flying
Sacrifice a creature: This creature gets +1/+1 until end of turn.

Chitin Gravestalker

This spell costs {1} less to cast for each artifact and/or creature card in your graveyard.
Cycling {2} ({2}, Discard this card: Draw a card.)

Caustic Caterpillar

{1}{G}, Sacrifice this creature: Destroy target artifact or enchantment.

Crash of Rhino Beetles

Trample
This creature gets +10/+10 as long as you control ten or more lands.

Lord Dregg, Insect Invader

Flying
Disappear — At the beginning of your end step, if a permanent left the battlefield under your control this turn, create a 1/1 black Insect Warrior creature token with flying.
{3}{G}, Sacrifice a token: Draw a card.

Heartstabber Mosquito

Kicker {2}{B} (You may pay an additional {2}{B} as you cast this spell.)
Flying
When this creature enters, if it was kicked, destroy target creature.

Moldgraf Millipede

When this creature enters, mill three cards, then put a +1/+1 counter on this creature for each creature card in your graveyard. (To mill three cards, put the top three cards of your library into your graveyard.)

Carrion Beetles

{2}{B}, {T}: Exile up to three target cards from a single graveyard.

Swarm Culler

Flying
Whenever this creature becomes tapped, you may sacrifice another creature or artifact. If you do, draw a card.

Insatiable Skittermaw

Menace (This creature can't be blocked except by two or more creatures.)
Void — At the beginning of your end step, if a nonland permanent left the battlefield this turn or a spell was warped this turn, put a +1/+1 counter on this creature.

Kraul Foragers

Undergrowth — When this creature enters, you gain 1 life for each creature card in your graveyard.

Carrion Grub

This creature gets +X/+0, where X is the greatest power among creature cards in your graveyard.
When this creature enters, mill four cards. (Put the top four cards of your library into your graveyard.)

Duskshell Crawler

When this creature enters, put a +1/+1 counter on target creature.
Each creature you control with a +1/+1 counter on it has trample. (It can deal excess combat damage to the player or planeswalker it's attacking.)

Insectoid Exterminator

Flying
Disappear — At the beginning of your end step, if a permanent left the battlefield under your control this turn, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Thawbringer

When this creature enters or dies, surveil 1. (Look at the top card of your library. You may put it into your graveyard.)

Swamp Mosquito

Flying
Whenever this creature attacks and isn't blocked, defending player gets a poison counter. (A player with ten or more poison counters loses the game.)

Nantuko Husk

Sacrifice a creature: This creature gets +2/+2 until end of turn.

Gene Pollinator

{T}, Tap an untapped permanent you control: Add one mana of any color.

Mortician Beetle

Whenever a player sacrifices a creature, you may put a +1/+1 counter on this creature.