Knot grass moth

Another lucky dip into remote corners of our species lists wins us the knot grass moth (Acronicta rumicis), a night flyer of open grassland and woodland edges.

The species is classified as common and widely distributed but its numbers are falling so it has been listed as a Priority Species in the UK Biodiversity Action Plan since 2007. There are 13 other UK BAP Priority Species of Lepidoptera on the reserve’s lists, all carefully monitored and catered for by lepidopterists Ian Bushell and Hugo Brook.

The adult knot grass moth can be seen on the wing from May to July. It is attracted to light so keep an eye out for it around your garden lanterns on summer evenings. In places as far south as Wiltshire, there is usually a second brood in flight by August and September.

Knot grass caterpillars are not fussy eaters. They feed on all kinds of herbaceous plants, including sorrel, dock, bramble, thistles and hop, all present and abundant in the reserve. They also eat crop plants like Prunus species fruit trees, maize and strawberries and in many parts of the world they are considered a serious agricultural pest.

In their turn, though, they are bird food, hatching from their eggs at just the right time to feed the nestlings of the reserve’s small insectivores: robins, tits and warblers. What goes around, comes around.

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