Diversity worries

But the giant weta from New Zealand holds the record as the heaviest insect. As a flightless insect, it has put on the bulk. A female measuring just 80 mm long has been recorded at 71 grammes. In perspective, most beetles at this length probably weigh 5 grammes and birds of this size would probably weigh 12 grammes. And, of course, the colonial insects break records. Jones notes that leafcutter ants have been found to create tunnels reaching 6 metres deep and comprising between 5 and 8 million workers. More unusual is the temperature dependence of the North American snowy tree cricket’s song. There are an estimated 20,000 species of crickets, katylids and grasshoppers in the world, each with its own unique song. Biologists thought the song was fixed for each species, but in 1897 the American inventor Thomas Dolbear determined that the number of calls directly related to air temperature, leading to this insect’s nickname as the thermometer cricket. And Jones notes some of the most remarkable insects, in terms of their environment. Sea skaters have taken the freshwater lifestyle of their relatives to extremes. About 45 species in the genus Halobates are known; they are all tropical and mostly live inshore in mangrove swamps. But five species have been found to venture out into the open ocean. Sea skater eggs have been found on many floating objects but human rubbish appears to be attractive. In 2002, Jones reports, an empty plastic milk container dredged from the middle of the Pacific Ocean, was found to have 70,000 sea-skater eggs. While adults are often the most visible parts of the insect life cycle, their larvae can have extraordinary and lengthy lives. The golden jewel beetle larvae, Jones notes, have been shown to live more than 50 years in timber. Jones also highlights the scarab beetles, which are among the few insects that have been revered by humans. They were special for the ancient Egyptians and used as the symbol for Cheper, the god of creation.