|Voiced by Lili Francks|
Arachnidia is Insectiva's twin sister. Unlike Insectiva, she loves arachnids, as her name suggests. She and Insectiva have had a bitter rivalry, and both pit their own respective arthropods against each other, with catastrophic results. She is the gothic version of Insectiva.
- First Appearance: Episode 27 "Sinister Rivalry"