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 is a common arthropod weakness. They lack internal skeletons, so Necromancers are unable to raise them as skeletons (they may still be zombified, however).
a Worker ant - Poisonous critters that seek out puny adventurers to drag back to their nests.
a Soldier ant - The sort of giant ant that can chomp through armour and shake off stab wounds. Extra poisonous!
a Queen ant - Less nimble than other ants, but comes with a highly venomous bite and is always guarded by her numerous offspring.
t Fire crab - Scuttling pyromaniac menaces that turn the Dungeon into a furnace with their firey breath.
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 easier to deal with.
y Hornet - An oversized wasp dyed red in the blood of its paralyzed victims.
y Spark wasp - Electric swarming insects capable of launching themselves as bolts of living lightning.
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 Ghost moth - Invisible psychic predators with debilitating poisons.
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 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.
a Formicid - Rarely-seen humanoid ants who are most notable for their ability to burrow through solid rock.
B Death scarab - Undead swarming vermin that drain life and speed with their bites.
B Boring beetle - Beefy, but easily avoided. They tended to turn any floor with rock walls to swiss cheese if left to their own devices.
s Giant mite - Bloated, poisonous vermin found in the early Dungeon.
w Killer bee larva - Virtually zero threat, much like ant larvae.
s Spider - Scuttling poisonous pests. Individually weak, but they came in swarms.
s Trapdoor spider - Cowardly vermin that struck at those who walked past their hiding places and retreated underground when injured.
s Giant centipede - Although fragile, their poison stings could be hazardous.
B Boulder beetle - Tanks that normally lumbered along slowly, but they could suddenly start rolling at break-neck speed.
y Wasp - Although slower and more solitary than killer bees, their stings slowed and paralysed their victims.
0.19 - Added meliai and removed wasps and boulder beetles
0.18 - Added spark wasps, removed trapdoor spiders and plain spiders.
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.