List of arthropods
Considering that the Dungeon is a dark, dank place filled with moist corners and rotting corpses, it's no surprise that it contains countless creepy-crawlies ranging in size from freakishly huge to terrifyingly gargantuan. Crawl's many arthropods are some of the weaker opponents you'll encounter, but they shouldn't be underestimated; a great many of them have poisonous bites or stings, more than a few also come with exotic and dangerous special abilities, and they tend to come in swarms. While there are some exceptions, vulnerability to Poison Magic is a common arthropod weakness. Many of them leave poisonous corpses, so Ignite Poison is also quite effective. They lack internal skeletons, so Necromancers are unable to raise them as skeletons (they may still be zombified, however).
Arthropods in general are fairly common throughout the Dungeon and the Lair, but certain varieties are quite common in other areas. The Spider's Nest, for example, is full of spiders.
Contents
Ants
B 
Worker ant - Poisonous critters that seek out puny adventurers to drag back to their nests.
B 
Soldier ant - The sort of giant ant that can chomp through armour and shake off stab wounds. Extra poisonous!
B 
Queen ant - Although a heavy hitter in melee, her slow speed makes her much less intimidating than her minions.
Beetles
B 
Boulder beetle - These tanks normally lumber along slowly, but they can suddenly start rolling at break-neck speed.
B 
Death scarab - Undead swarming vermin that trail miasma and drain life and speed with their bites.
Crabs
t 
Fire crab - Scuttling pyromaniac menaces that turn the Dungeon into a furnace with their fire breath.
t 
Ghost crab - Dark-tainted fire crabs which spew ghostly fire, harming the living and summoning hostile spirits.
t 
Apocalypse crab - Rare Abyss-dwellers that bathe their prey in the unpredictable forces of raw chaos.
Flying Insects
y 
Killer bee - Painful alone and deadly in swarms, these pack hunters are a menace to the unprepared.
y 
Queen bee - Although extremely venomous, her lack of maneuverability makes her easy to deal with.
y 
Wasp - Although slower and more solitary than killer bees, their stings slow and paralyse their victims.
y 
Hornet - An oversized wasp dyed red in the blood of its victims.
y 
Spark wasp - Electric swarming insects appearing in Spider and Depths.
y 
Vampire mosquito - Pesky undead insects that will happily suck the unwary dry.
Moths & Butterflies
b 
Butterfly - Harmless and pretty and occasionally in the way.
y 
Moth of wrath - These fluttering nuisances are capable of enraging anything they come across.
y 
Ghost moth - Invisible psychic predators with debilitating poisons.
Spiders
s 
Spider - Scuttling poisonous pests. Individually weak, but they come in swarms.
s 
Jumping spider - A hyperactive spider which leaps in and out of combat, covering you in sticky silk all the while.
s 
Trapdoor spider - Cowardly vermin that strike those who walk past their hiding places and retreat underground when injured.
s 
Tarantella - Strange spiders with bites that disorient their prey.
s 
Redback - A notoriously venomous arachnid, capable of seriously poisoning even those who are resistant.
s 
Wolf spider - A powerful spider capable of tearing foes apart even without its venom.
s 
Orb spider - Cowardly, unnatural spiders that launch orbs of devastating energy at their foes.
Unique Spiders
H 
Arachne - Formerly human, this hybrid creature rules over and defends the Spider's Nest with powerful Poison Magic and endless webbing.
Other Arthropods
B 
Giant cockroach - Common pests of the upper floors of the Dungeon, they're mostly harmless.
s 
Scorpion - One of the earliest opponents capable of seriously poisoning careless adventurers.
s 
Demonic crawler - Swift, hellish arthropods that partially resist most elements, including poison.
s 
Emperor scorpion - The beefiest arthropod of them all, they shrug off blows that would fell lesser bugs.
B 
Entropy weaver - Odd arachnoid casters that know a slow, ancient chant that can rapidly corrode their foes' equipment.
Retired Arthropods
a 
Ant larva - Baby ants that were about as threatening as a goblin with three limbs missing.
B 
Boring beetle - Beefy, but easily avoided. They tend to turn any floor with rock walls to swiss cheese if left to their own devices.
k 
Bumblebee - Bigger, solitary bees with a much less terrifying history of player deaths than the killer variety.
b 
Chaos butterfly - Dangerous Abyssal butterflies that created raging storms with every flap of their wings.
k 
Giant firefly - Flying insects notable for their signal flash and their use as mounts for spriggan riders.
s 
Giant mite - Bloated, poisonous vermin found in the early Dungeon.
B 
Goliath beetle - Slow enough for even nagas to kite, but durable enough to make you wonder if it's worth the effort.
y 
Polymoth - Fluttering menaces that constantly polymorph nearby monsters. Exist in 0.13 but are disabled, and were removed in 0.14.
y 
Moth of suppression - Sickly moths that suppressed all magical items within their zone of effect.
s 
Giant centipede - Although fragile, their poison stings could be hazardous.
History
0.18 - Added spark wasps.
0.17 - Added entropy weavers, removed giant mites, boring beetles and goliath beetles.
0.16 - Added death scarabs, renamed yellow wasps and red wasps to wasps and hornets, respectively.
0.15 - Added ghost crabs, removed giant fireflies.
0.14 - Removed giant centipedes and moths of suppression.
0.13 - Added and quickly removed polymoths.
0.12 - Added moths of suppression and chaos butterflies, and removed bumblebees and ant larvae. Chaos butterflies were removed soon after due to flooding issues.
