Tree trunk spiders (Hersiliidae) is a tropical and semi-tropical family first described by Tamerlan Thorell in 1870. They have two prominent spinnerets that are almost as long as their abdomen, earning them the nickname "two-tailed spiders". They range in size from 10 to 18 millimetres (0.39 to 0.71 in) long. Rather than using a web that captures prey directly, they lay a light coating of threads over an area of tree bark and wait for an insect to stray onto the patch. When this happens, they encircle their spinnerets around their prey while casting silk on it. When the insect is immobilized, they can bite it through the shroud. Wikipedia