The Insectoid Grimoire is a monstrous bestiary and campaign toolkit for Dungeons & Dragons 5e, crawling with instinct-driven horrors that do not speak, do not serve, and do not stop. This book reimagines bugs not as background vermin, but as apex predators, siege engines, parasitic overlords, and hive-born swarms that infest every biome—evolving, multiplying, and feeding on the world that tries to contain them.
Whether you need a living dungeon, a wilderness arc infested with filth-born rot, or a campaign-wide threat that spreads like wildfire beneath your cities, this book gives you everything you need to make insectoids central to your narrative—and unforgettable in your encounters.
Overview. What makes insectoids distinct, terrifying, and essential? Learn how to integrate them as centerpieces, complications, or creeping inevitabilities in any campaign.
A History of Insectoids. Trace the lineage of bug horror from real-world parasitoids to their evolutions in D&D lore. Understand the archetypes—scouts, hive queens, flesh eaters—and how to use them as narrative tools.
Incorporating Insectoids Into Your Campaign. Whether as wilderness complications or world-ending infestations, this section provides narrative strategies and mechanical scaffolding to insert insect threats at any scale.
Insects do not rally under banners. They have no cults, no gods, and no warcries. They have hunger. They have cycles.
No Flags, No Faith, Only Function. Why insectoids transcend politics and ideology, and how that makes them uniquely horrifying.
Species Profiles. Ants, Beetles, Flies, Roaches, Spiders, Wasps, and Exotics—each with their history, goals, and dominant biological leaders.
A swarm of brand-new monsters, built from the ground up. Every creature is fully illustrated, deeply described, and tactically distinctive.
189 Original Stat Blocks, CR 1/2 to 12
Divided by species: Ants, Beetles, Flies & Mosquitos, Roaches, Spiders, Wasps, and Exotics
Includes Boss-tier monsters at CR 4, 8, and 12 for each group
All monsters include special abilities, combat tactics, behavioral notes, and descriptions
Swarmmothers, siege beetles, larval invaders, psychic spiderlings, parasitic drones, tunnel beasts, and more
These aren’t enchanted rings or glowing swords. These are glands, shells, mandibles, and scent-based tools made from the bugs themselves.
20 New Magic Items, from Common to Very Rare
Items affect pheromones, terrain, swarm manipulation, larval prevention, and more
Perfect for campaigns where bugs are the threat—or where you want to fight like them
You don’t need to reinvent the wheel to terrify your players. Just let the insects evolve.
Infestation Tables. How nests spread, day by day
Hive-Building Systems. Dungeons that grow and retaliate
Larval Timer Mechanics. What happens when the bite goes too deep
Environmental Reactions. How the world shifts under insect rule
Swarm Encounter Engine. Run area-wide infestations without tracking dozens of creatures
Bug-Type Behavior Templates. Run smarter, instinct-based monsters with just a glance
Pheromone-Based Stealth. Tools and mechanics for infiltration, control, and deception
Post-Combat Consequences. What happens after the stinger lands
Hive Evolution Tables. Full-scale growth arcs, from scout phase to larval gods
Because monsters that think can be bargained with.
Because monsters with religion can be reasoned with.
Insectoids don’t think. They act.
This is more than a monster manual—it’s an ecological crisis in stat block form. A compendium of swarm, instinct, mutation, and rot. A plague with a pulse.
189 custom stat blocks
20 biologically themed magic items
9 campaign-ready DM tools
21 boss-tier insectoids
7 complete species categories
One unstoppable infestation
They don’t want your treasure.
They want your tunnels.
And they are already inside.
License: Roll20 End User License Agreement
(Personal Use Only, Do Not Distribute)
