Witcher Wiki
Armored arachasae
Tw3 journal armoredarachas
Details
Class
Insectoid
Variations
Arachas
Venomous arachas
Harrisi
Vulnerable to
Golden oriole
Insectoid oils
Tactics
spits webbing
Loot
Arachas eyes
Chitinous shell
Monster heart
Monster saliva

The Illustrated Atlas of Insectoids provides this bestiary entry.

Bestiary entry[ | ]

That's the kinda john we call an 'armored arachas.' Hard and prickly on the otuside, but get 'im undressed and everything's soft and squishy.
— Foxy Lisa, Maribor prostitute
An arachas' only weakness is its soft, sensitive abdomen. Some arachasae hide this under hollow tree stumps, while other, "armored" varieties exist which have grown a thick carapace that covers all the more delicate parts of their bodies.
An armored arachas is a true behemoth. It uses its enormous mass to knock over and trample its victims then devours their crushed remains. Like all arachasae, it is highly venomous, and this Golden Oriole should always be consumed before fighting it.
It is also worthwhile to stock up on healing potions and crossbow bolts before setting out, for this arachas' thick plating can withstand a great deal of damage, making battles with it a long and exhausting affair.