The notorious black widow spins two very different sorts of webs. The basic design consists of a horizontal sheet with vertical lines underneath, stuck to the floor with blobs of glue. These threads are incredibly taut. If an insect blunders into them, they break, stick to the insect and catapult it into mid-air, where the spider can kill it leisurely. This structure is only woven by hungry spiders. Well-fed ones spin a more chaotic tangle of non-stick threads. It’s a completely different design and akin to a silken fortress, providing the spider with better defences when it has already ensnared its fill of food. The black widows might even change the architecture of their lairs to stop themselves from overeating.