The tree trunk spiders are members of the tropical and semi-tropical Family Hersiliidae. There are about 150 species in this family. These spiders have two very prominent spinnerets that are almost as long as their entire abdomens. So they are also sometimes known as "two-tailed spiders." They range in size from about 10 mm (0.4 inch) to 18 mm (0.7 inch)long. Being very well camouflaged for life on the varicolored trunks of trees, they have an interesting way of capturing prey. Rather than making a web that captures prey directly, they lay a light coating of threads over an area of tree bark and wait hidden in plain sight for an insect to stray onto that patch. Once that occurs, they direct their spinnerets toward their prey and circle it all the while casting silk on it. When the hapless insect has been thoroughly immobilized they can bite it through its new shroud. Spiders that live in trees.