Spodoptera litura

Spodoptera litura (Fabricius, 1775)
Cluster Caterpillar
(one synonym : Prodenia tasmanica Guenée, 1852)
ACRONICTINAE, NOCTUIDAE, NOCTUOIDEA

Don Herbison-Evans
(donherbisonevans@yahoo.com)
and
Stella Crossley

third instar

Initially, the Caterpillars are a translucent green with a dark mark on the thorax.

later instar
(Photo: courtesy of Harold McQueen, Goodna, Queensland)

Later instars are smooth-skinned with a pattern of red, yellow, and green lines, and with a dark patch on the mesothorax.

close-up of head
(Photo: copyright Lyn Finn,
Hunter Region School of Photography in Newcastle,
Macquarie Hills, New South Wales)

Initially the caterpillars only eat the flesh of their food leaves, leaving the veins intact. Later, as they grow, they eat whole leaves, and even flowers and fruit. The caterpillars become brown with three thin yellow lines down the back: one in the middle and one each side. A row of black dots run along each side, and a conspicuous row of dark triangles decorate each side of the back.

penultimate instar, lateral view
(Photo: copyright Lyn Finn,
Hunter Region School of Photography in Newcastle,
Macquarie Hills, New South Wales)

The caterpillars are an international pest and eat nearly any herbaceous plant, including :

Leek ( Allium porrum, ALLIACEAE ),

Spider Lilies ( Crinum pedunculatum, AMARYLLIDACEAE ),

Elephants Ear ( Alocasia macrorrhizos, ARACEAE ),

Lettuce ( Lactuca sativa, ASTERACEAE ),

Cabbage ( Brassica oleracea, BRASSICACEAE ),

Horsetail She Oak ( Casuarina equisetifolia, CASUARINACAE ),

Beetroot ( Beta vulgaris conditiva, CHENOPODIACEAE ),

Sundew ( Drosera species, DROSERACEAE ),

Peanuts ( Arachis hypogaea, FABACEAE ),

Geranium ( Pelargonium x zonale, GERANIACEAE ),

Cotton ( Gossypium hirsutum, MALVACEAE ),

Banana ( Musa acuminata, MUSACEAE ),

Fuchsias ( Fuchsia species, ONAGRACEAE ),

Strawberry ( Fragaria ananassa, ROSACEAE ),

Tomatoes ( Lycopersicum esculentum, SOLANACEAE ), and even

Mosses ( BRYOPHYTA ), and

Ferns ( POLYPODIOPHYTA ).

penultimate instar, dorsal view
(Photo: copyright Lyn Finn,
Hunter Region School of Photography in Newcastle,
Macquarie Hills, New South Wales)

The last instars are very dark, with four prominent yellow triangles on the thorax.

(Photo: courtesy of Brent Meads, Perth, Western Australia)

When disturbed, the caterpillar rears up and curls its head under its body.

defensive posture
(Photo: courtesy of Rick Speare, Topaz, Queensland)

If further disturbed, it curls into a tight spiral with the head protected in the centre.

When mature, the caterpillar burrows into the soil below the plant for several centimetres and there pupates without a cocoon. As it does so, it produces a quantity of fluid, and will drown in this if it pupates in captivity in an empty glass jar. It will pupate successfully if 0.5 cm. of sand is provided in the container.

(Photo: courtesy of the Macleay Museum, University of Sydney)

The duration of the pupal stage in January in Melbourne is three weeks, but caterpillars that pupate at the end of summer emerge the following spring.

Female
(Photo: courtesy of David Rentz, Kuranda, Queensland)

The adult moth is brown with a complex pattern of cream streaks criss-crossing the forewings. The hindwings are silvery white. The moth has a wingspan of about 4 cms.

Male
(Photo: courtesy of John and Susanne Mansfield, Black Head, New South Wales)

The males but not the females have a blue-grey band from the apex to the hind margin of each forewing.

Female
(Photo: courtesy of Nick Monaghan, Tewantin, Queensland)

The pheromones of this species have been elucidated.

Female
(Photo: courtesy of CSIRO/BIO Photography Group, Centre for Biodiversity Genomics, University of Guelph)

The eggs of this species are normally laid in an irregular furry mass on the underside of a leaf of a foodplant.

egg mass with first instar caterpillars

For small numbers of plants: the best control is to pick the caterpillars off and deposit the caterpillars somewhere else where they will cause no concern. Also inspect leaf undersides every day and pick off leaves with egg masses on them.

We recommend against using insecticides, which may leave residues in the fruit harmful to to humans, as they reduce the parasite and predator populations next year: so are not a long term solution.

Various other methods of control have been investigated :

planting near Derris and Garlic plants,

breeding resistant Groundnuts from wild Groundnut strains,

breeding resistant Groundnuts using bacterium Bacillus thuringiensis genes,

using a Baculovirus ( BACULOVIRIDAE ),

the nematode Steinernema carpocapsae ( STEINERNEMATIDAE ), and

the fly Exorista japonica ( TACHINIDAE ).

Cocos Islands 1982

The species occurs across south-east Asia and the Pacific, including:

as well as in Australia in

Australian Capital Territory,

Victoria, and

Tasmania.

In Sydney, New South Wales, counts were made of the number of adults coming to a nightly ultra-violet light, and the numbers totalled for each month of the year :

Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec
7	8	12	5	6	1	0	0	0	0	1	3

These indicate that there is only one brood a year in that area.