Three moth species have disappeared from the U.K. in the past decade and two thirds of the species that remain have suffered dramatic population crashes according to new research from the organizations Butterfly Conservation and Rothamsted Research. The news is published in the new report "The State of Britain's Larger Moths 2013" (pdf), which covers the roughly 900 "macro moths" out of the 2,500 moth species recorded in Great Britain.
The three moth species cited in the report as extinct in the U.K. are the orange upperwing (Jodia croceago), the bordered gothic (Heliophobus reticulate) and the Brighton wainscot (Oria musculosa). The organizations suspect that a fourth species, the stout dart (Spaelotis ravida), may have also disappeared. All four of these species had limited ranges and had been in decline for decades. They follow 62 other U.K. moth species that went extinct in the 20th century. Habitat loss, especially related to industrial farming in the southern half of the U.K., appears to be the primary driver of the extinctions, although pesticide use could also be a factor. The total number of all large moths has fallen by 43 percent in the southern U.K. since 1968, compared with just 11 percent in the north.
Additional extinctions could soon follow, the report warns. The population of V-moths (Macaria wauaria) has declined by 99 percent since 1968. The garden dart (Euxoa nigricans), the double dart (Graphiphora augur) and the dusky thorn (Ennomos fuscantaria) have all declined by 98 percent. Numerous other species face similar declines. All told, 61 species of larger moths have declined by 75 percent or more since 1968.
Interestingly, one third of large moth species are actually enjoying population increases and a few species have had dramatic population expansions. The number of least carpet moths (Idaea rusticata) has grown by nearly 75,000 percent (that's not a typo) over the past 40 years, making it by far the biggest winner amongst British moths. The reasons for this particular boom are unknown, but the organizations theorize that other species—including 27 non-native species that have come to the British Isles during the 21st century—may be benefitting from climate change as certain habitats become warmer and more hospitable. Non-native plants in parks and gardens have also helped these "colonizers" to gain territory in the U.K.
Why should we care about moth extinctions? Moths help to pollinate native plants and serve as an important source of food for birds, bats and other species, Butterfly Conservation vice president Chris Packham said in a prepared statement. On a broader scale, "Larger moths are key indicator species that let us know how our environment is faring in a period of unprecedented environmental change," he said.
The information for this report was generated through the long-running Rothamsted Insect Survey, which taps volunteers and citizen scientists to help monitor insect populations throughout the U.K.
Photos courtesy of Butterfly Conservation. Used with permission