The profusion of insects in the twisted city-state is hard to explain; most are little more than an irritation, the constant noise of some has caused madness. Their sheer number and variety here is perhaps why so many have phobias about them; the enormous spiders found lurking under eaves, things with too many legs seen chasing dogs down dark alleyways, the stories about pigs being stripped of flesh...
Whatever might be the truth, a certain aspect of insects here has an even more curious effect, some might even say boon—the local curiosity that is insectum, sometimes referred to as Vermis Insectum by certain scholars.
Here’s a short extract from the GM's Guide section entitled Insects and Insectum…
One of the more unique aspects of the Blight is the use and profligacy of insects in life. Insectum is a powerful ally in many ways; their poisons can enhance or debilitate, and as they are not generally magical abilities, they can stack with magical enhancements.
More mundane insects are everywhere in the Blight, a peculiarity even the wisest find difficult to explain. In summer the night air boils with them, whilst even in the depths of winter a hive of enormous elephant cockroaches may be seen huddling behind a hearth, or a black batmoth fluttering around a pyrelantern glow in the snow.
Insects are peculiarly large in the Blight, and unique. They have an alarming habit of swarming, and occasionally such swarms have stripped the flesh from a dog or small child, as well as killed adults in their anger.
The chart below lists the more common type of Insectum. In each case the insect is used as a leech would be—a live attachment with beneficial (or deadly) effect (Bi)—or is swallowed (I). Insects that bite cause the damage listed as well as the bane. In each case the insectum has a boon, which it grants for a given time, as well often (but not always) a penalty for its use. The price listed is the common price—insectum dealers vary their prices by demand and as few official dealers are granted a license by their corrupt guild (the Insectum Guild). A host of illegal street dealers peddle their cheaper wares, which are often more unpredictable in quality. Imbibers or attachers should beware of these disreputable dealers; they sell inferior, sick or even dangerous insectum, and whilst even guild members are not spotless, they do at least have the fear of stripping their guild status and of having (generally) a fixed address or place of work….
Here’s a tiny sample of insectum based on the Pathfinder rules, these from the GM’s Guide for the Jumble….
Beneath Bloated Centipede Mite: (Type Bi; Boon +4 to all Perception checks involving smell for 2 hours; Penalty large ugly mite is attached to and bites the inner nose and must remain attached for duration of effect; Cost 30gp)
Great Blight Hunstman Spider:(Type Bi; Boon poison heightens senses, gain Alertness feat for 4 hours; Penalty allowing the enormous spider (which can grow up to a foot across (encumbrance 3lbs)) to deliver its bite is revolting, the bite is mildly poisonous (save DC 12, damage 1d3 Dex); Cost 250gp. The price can be raised to 400gp to enable the spider to be kept alive for a period of 12 months, during which time its poison bite can be delivered once a day)
Lyme Water Hornet: (Type Bi; Boon hornet dies when it bites (stings), but grants the victim +1 Dex for an hour; Penalty—; Cost 50gp)