Knot Grass (Acronicta rumicis (Linnaeus, 1758))
Scientific name: Acronicta rumicis (Linnaeus, 1758)
Common name: Knot Grass
French name: Noctuelle de la patience, Cendrée noirâtre
Order: Lepidoptera
Suborder: Heterocera
Family: Noctuidae
Subfamily: Acronictinae
Wingspan: 34-44 mm.
Biotope: Meadows, hedgerows, parks and gardens.
Geographic area: Europe north to central Scandinavia, North Africa, Asia east to Japan.
Flight time: April-May then July-September.
Number of generations : 2 (only 1 in the northern part of the range).
Caterpillar: It shows tufts of russet or brown hairs and large dorsal white marks. There is a whitish longitudinal stripe with reddish orange spots on the sides of the body. The head is black with brown marks.
Host plant: Many herbaceous or ligneous plants: Broad-leaved Dock (Rumex obtusifolius), Ribwort Plantain (Plantago lanceolata) , Bramble (Rubus fruticosus), Brown Knapweed (Centaurea jacea), Common Dandelion (Taraxacum officinale), Goat Willow (Salix caprea), Hawthorn (Crataegus monogyna), etc.
The Knot Grass is variable in colour.
The forewings are mottled with pale and dark grey.
The median lines are indistinct.
There is a small comma-shaped white mark next to the inner edge.
The subterminal line is made by a series of white dots.
The hindwings are brown.
Imagos are sometimes attracted to light and visit flowers.
During the day, they are used to resting on trunks of trees or fence posts.
The Knot Grass over winters as a pupa.

Knot Grass (Acronicta rumicis) - Yvelines, France - August 31st 2013
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Knot Grass (Acronicta rumicis)
Young caterpillar.


Knot Grass (Acronicta rumicis) - Yvelines, France - August 31st 2013
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Knot Grass (Acronicta rumicis)
Upper side view of the same caterpillar.


Knot Grass (Acronicta rumicis) - Yvelines, France - September 15th 2013
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Knot Grass (Acronicta rumicis)
After two weeks of growth compared to the two previous pictures.


Knot Grass (Acronicta rumicis) - Yvelines, France - September 23rd 2007
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Knot Grass (Acronicta rumicis)
I have planted a few aster plants in my garden to attract some butterflies wanting to gather nectar. I haven't seen any imago but the Aster was used as host plant by the Knot Grass' caterpillar.


Knot Grass (Acronicta rumicis) - Yvelines, France - September 23rd 2007
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Knot Grass (Acronicta rumicis)
Birds must not chase this caterpillar as I have always observed it clearly visible on the plant.


Knot Grass (Acronicta rumicis) - Yvelines, France - October 5th 2013
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Knot Grass (Acronicta rumicis)
Upper side view.

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