Stalking prey
Most hunting spiders locate prey by searching randomly or by responding to vibrations. Wolf spiders and jumping spiders have keen eyesight. The latter stalk their prey to within 5 to 10 cm (2 to 4 inches) and then pounce when it moves. Many crab spiders wait for prey on flowers of a color similar to their own. They use their legs to grasp an unsuspecting insect and then give it a lethal bite.
Unique among the hunters are the spitting spiders (family Scytodidae). When these spiders encounter prey, they touch it, back off, and shoot a zigzag stream of sticky material over it. The sticky material, produced by modified venom glands in the cephalothorax, emerges from pores near the tips of the fangs located on the chelicerae. As the victim struggles, the spider approaches cautiously and bites the entangled insect.
Some ambush predators use silk to capture prey utilize various techniques. Ground-dwelling trap-door spiders construct silk-lined tubes, sometimes with silk trapdoors, from which they dart out to capture passing insects. Other tube-dwelling spiders place silk trip threads around the mouth of the tube. When an insect touches these threads, vibrations inform the spider of a victim’s presence. Funnel-weaving spiders live in silk tubes with a narrow end that extends into vegetation or a crevice and an expanded sheetlike end that vibrates when an insect walks across it.
Bolas spiders (Mastophora, Ordgarius) utilize silk as ambush predators. They release a single thread with a sticky droplet at the end and hold it with one leg. Some species swing this “bola,” and others throw it when a moth approaches. Male moths are attracted to this spider by its odor, which mimics that of female moths.