How does the author use foreshadowing in Perdido Street Station?

In a bit of foreshadowing, Isaac buys an unknown insect larva sold by a government clerk who has stolen it from a box shipped to Parliament. Isaac takes the slug to his laboratory and places it among his already-huge menagerie of flying insects and animals while he researches crisis energy as a possible way to provide powered flight for Yagharek. Neither is aware that the shipment of grubs is for a scientist, Dr. Magesta Barbile, who is engaged in research on slake moths, predatory mutants which grow large and have a taste for human brains as a way to extract their dreams. The moths' excrement is known in the underworld as dreamshit, and is a highly-addictive hallucinatory drug.