Small Tortoiseshell (Aglais urticae)

The Small Tortoiseshell is a very mobile species that can be found almost anywhere and is a frequent sight in gardens and visitor to Buddleia bushes. Larvae feed gregariously on Stinging Nettle (Urtica dioica) in open sunny situations. (For further details on this species see http://www.butterfly-conservation.org/).

Family: Nymphalidae

Status: Stable

Status details:
Status since 1976 is Stable with a decrease of -38.6%
Status over the last 20 years is Rapid decline with a decrease of -58.6%
Status over the last 10 years is Stable with a decrease of -55.8%

Trend description:
The data show no significant trend but they do show that this butterfly fluctuates greatly in numbers, often from year to year. Following the high index of 1997 the Small Tortoiseshell index fell to its all-series low in 1999. There were fears that an introduced parasite of Nymphalid butterflies, the Tachinid fly Stumia bella, which was first recorded in Britain in 1998, might be having an adverse effect on this butterfly. However numbers climbed steadily after that, and the 2003 index was the sixth highest in the series. Although the parasite is now found all over southern Britain there is no evidence so far that the parasite is badly affecting any Nymphalid species.

In total, Small Tortoiseshell has been recorded from 897 transects in the Butterfly Monitoring Scheme. Of these, annual indices of abundance have been calculated from 1035 sites, with an average index of 29 individuals per site.

For 469 of these sites, Small Tortoiseshell has been recorded well enough to calculate annual indices of abundance in 6 or more years, allowing trends to be calculated.

In 2006, 6636 individuals were recorded from 535 sites, producing annual indices at 386 of these.

Links to counts

1973, 1974, 1975, 1976, 1977, 1978, 1979
1980, 1981, 1982, 1983, 1984, 1985, 1986, 1987, 1988, 1989
1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999
2000, 2001, 2002, 2003, 2004, 2005, 2006