These famously venomous spiders build another variety called a sheet web. It consists of a horizontal sheet of silk supported by threads going up to some support. Underneath, the black widow creates taut threads that hang down to the ground where they’re attached by sticky glue. If an insect bumps into one of these, it detaches from the ground, sticks to the intruder, and leaves it dangling. The spider feels the vibrations through the sheet and heads down for dinner.