However between the early 1960s and late 1980s the population of I. mutans was shown to have decreased significantly, by over 80%, at two study sites.

[2] Some of these subsequent names, H. lignifusca, M. acceptrix and H. debilis, were synonymised by Edward Meyrick in 1887 when he transferred the species to the genus Mamestra.

Sometimes these markings are hardly visible, and the larva is entirely green, whilst occasionally the brown colouring predominates.

[6]Walker in his original description of I. mutans described the adult of the species as follows: Male and female.

Fore wings with the disk hardly clouded; black stripe obsolete, except at each end.

[8] The larvae feed on a variety of herbaceous plants including those used to create pasture for stock, weeds such as Pilosella officinarum, as well as crops such as turnips, peas, wheat, and the leaves and fruit of apple trees.

[6] The length of time this species in the pupal state depends on the season in which it pupates as well as what part of the country.

[6] If in summer it can be a short period of time, but if in autumn the adult does not emerge until the following spring.

[11] A recent study suggests this moth may be assisting with the pollination of avocado trees.

[2] In 1991 the entomologist Graeme White published a paper documenting population declines in this species at two sites of between 84% and 91% during 1962 and 1989.