Changes in macro-moth abundance on the Writtle College estate, 1968-1993
Fig. 1. Total number of individuals and species recorded each year
Only 18 species had more than 500 individual moth records for the monitoring period (Table 1) with
their total numbers of 23,185 comprising 58% of the total number of individuals captured. The most
common species were Heart and Dart Agrotis exclamationis and Common Wainscot Mythimna
pallens which combined, formed approximately 14% of the total numberof moths recorded over the
monitoring period. Nine of these common species were recorded every year (Table 1) with some
apparently common species such as Willow Beauty Peribatodes rhomboidaria being absent in sev-
eral years.
However, 63 species were recorded only once, with six species that arc currently included in the
Regional Action Plan for Anglia as priority species (Joy & Bourn 2000) being identified (Table 2).
Some of these species such as Large Thorn Ennomos autumnaria and Waved Black Parascotia
fuliginaria were recorded in the early 1990s and possibly still have colonies in Essex. Three other
priority species were recorded over the monitoring period (Table 2).
Many of the common species experienced dramatic fluctuations in numbers with M. pallens being
captured at relatively low numbers in most years, except in 1975 and 1976 when numbers peaked
at 780 and 761 respectively, only to decrease to 14 records in 1977 (Figure 2).
Fluctuations in numbers were also noted for Lunar Underwing Omphaloscelis lunosa which displayed
three peaks in numbers (Figure 3).
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Essex Naturalist (New Series) 18 (2001)