turbing decline in both numbers of individuals (4–500 in the late 1980s and early 1990s, but 1–300 since 1994) and number of species (over 20 in the late 1980s and early 1990s but 4 or less since 2004).
Butterfly counts in Northern California have also shown a serious decline. In 2006, Dr. Arthur Shapiro at UC Davis reported fewer butterflies in Northern California, particularly in the Central Valley, than at any time since he started counting them 35 years ago. At most of his study sites, he found only about half, or less than half, the number of species present in an average year. Near Vacaville in 2005, he found 378 individuals of 21 species, but in 2006 there were 43 individuals of 10 species (Kay, 2006).
Headlines like “Where have all the butterflies gone” are showing up in newspapers and journals in many other countries, including India (Khanna, 2005), Japan (Inoue, 2005), Canada (Science Daily, 2007), Australia (http://www.samuseum.sa.gov.au/butterflies/butterfly.htm), New Zealand (New Zealand Herald, 2007) and Britain (Butterfly Conservation, 2007a). The reasons for butterfly decline are usually not known, although pesticide use, genetically modified crops, climate change, habitat destruction, drought, and excessive collecting for trade are among the known causes or suspects.
In Britain, with a long tradition of public engagement in wildlife observation, over 10,000 volunteer recorders participate in assessing the distribution and abundance of butterflies over a network of over 750 geographic sites (http://www.butterfly-conservation.org/text/36/recording_monitoring.html), using a combination of weekly transect counts and single-visit timed counts. The comprehensive 2007 report (Fox et al., 2007) shows that many of Britain’s butterflies are, unfortunately, in a rapid and alarming decline. The Large Blue became extinct in 1979 and has been successfully reintroduced, but 76% of the 54 remaining resident species have declined. A related moth monitoring program including a National Moth Night assesses the distribution of moths throughout the country. Moths are much more diverse than butterflies, with about 2,500 species, and are not as well known but their numbers have also dropped, by about a third since 1968 (Butterfly Conservation, 2007b). Some moth species are seriously endangered and a few are thought to have gone extinct. British insect species that have disappeared in the past 50 years include 88 beetles, 56 butterflies and moths, 20 bees, 17 flies, 14 bugs and hoppers, and 12 wasps (McCarthy, 2006) making a total of over 200 extinctions. Three bird species and 20 plants have also been lost.
Sightings of butterflies by hundreds of volunteers are contributing to our understanding of climate change. This was seen most clearly in Britain, where April 2007 was the warmest April on record ending the hottest 12 months ever recorded. Associated with this climate change, 11 species of butterflies made their earliest recorded appearances and of 59 resident