Butterflies and moths are insects in the order Lepidoptera, meaning “scale winged” in Greek for the tiny scales covering their wings and body. Like all insects, Lepidoptera have a hard outer covering called an exoskeleton which is divided into sections with joints so the animal can move. Also like other insects, butterflies and moths have six legs, a head, a thorax, and an abdomen. They are found on every continent except Antarctica, and in nearly every environment, where they serve an important role in food chains.
Recently compiled estimates of described species suggest there are ~150,000 to 160,000 Lepidoptera species, compared to ~115,000 to 120,000 ant, bee and wasp (Hymenoptera) species. (Zhang, 2011)
- Zhang, Z.-Q. 2011. Animal biodiversity: An outline of higher-level classification and survey of taxonomic richness. Zootaxa(3148): 1-237. http://www.mapress.com/zootaxa/list/2011/3148.html
- Florida Museum of Natural History, Lepidoptera, http://www.flmnh.ufl.edu/education/guides/butterfly-guide.pdf, accessed 31 May 2012
- See also Encyclopedia Britannica, Lepidopteran, http://www.britannica.com/EBchecked/topic/336811/lepidopteran/39726/Size-range-and-distribution/ , accessed 31 May 2012
More recently compiled estimates of described species suggest Lepidoptera and Diptera probably both ~150,000 to 160,000, Hymenoptera ~115,000 to 120,000. Zhang, Z.-Q. 2011. Animal biodiversity: An outline of higher-level classification and survey of taxonomic richness. Zootaxa(3148): 1-237. http://www.mapress.com/zootaxa/list/2011/3148.html
I wonder whether it is true that there are more species of Lepidoptera than Diptera or Hymenoptera. Given the large numbers of undescribed species in each of these groups, it's hard to know, but is this even true considering only described species? Seems plausible, but I wonder whether anyone has made a recent tabulation (I see in E.O. Wilson's 1992 book Dversity of Life, on p. 136 he gives the relevant numbers as: Lepidoptera 112,000; Hymenoptera 103,000; Diptera 98,500)