Spiders are superb artisans, weaving ethereal webs from silk finer than human hair. Now it appears that arachnids also excel at making chemical weapons. Researchers have found that the golden orb-web spider (Nephila antipodiana), a species common in tropical Asia, coats its silk with a toxic substance to deter hungry ants. The secret ingredient is a compound known as 2-pyrrolidinone, which is also made by gypsy-moth caterpillars to ward off predatory ants. When the researchers presented three types of ants with spider-silk "bridges," the insects refused to cross those soaked in 2-pyrrolidinone, the team reports online today in the Proceedings of the Royal Society. The chemical is probably physically unpleasant to the ants' antennae, which helps the spiders keep their meals to themselves.
See more ScienceShots.