Spodoptera mauritia (Boisduval, 1833)
(one synonym : Prodenia acronyctoides)
Lawn Armyworm

Don Herbison-Evans
Stella Crossley

These eggs were laid on the painted wall of a house, as a hairy irregular mass about 0.5 cms. across. The baby Caterpillars were white with big black heads, about 0.1 cm long. They descended from the wall on silken threads.

The young Caterpillars are smooth-skinned and green with longitudinal lines.

Later, the Caterpillars become brown with two rows of black triangles down the back. When disturbed, they drop, and curl into a spiral with the head in the middle.

They are an international agricultural pest on crops and pastures, feeding on plants from the family POACEAE such as:

  • Bermuda Grass ( Cynodon species ),
  • Kikuyu ( Pennisetum clandestinum ),
  • Sorghum ( Sorghum bicolor ), and
  • Rice ( Oryza sativa ),

as well as:

The Caterpillars grow to a length of about 3 cms. They burrow into the soil below the plant where they pupate without a cocoon.

The adult moth is brown with a complex pattern of light marks on the forewings. The hindwings are plain pearly white. It has a wingspan of about 4 cms.

The moth is preyed on by a Bolas Spider ( Celaenia species, ARANEIDAE ). This spider swings a silk thread with a sticky knob on the end, and emits a copy of the female moth’s pheromone to attract the male moths.

Attempts to control the pest include the use of:

  • some sacking laid near the plants attacked, so that the Caterpillars will hide under that by daytime, and they may be then collected and disposed of, or
  • a garden roller at midnight (when they come out to feed),
  • Hormones,
  • its Nucleopolyhedrovirus ( BACULOVIRIDAE ),
  • the nematode Steinernema carpocapsae ( STEINERNEMATIDAE ),

The species occurs around the world, including:

  • Borneo,
  • Hawaii,
  • India,
  • Malaysia,
  • Seychelles,
  • Thailand,
  • U.S.A.,
    as well as the north and east of Australia, including :
  • Norfolk Island,
  • Northern Territory, and
  • Queensland.

In Sydney, 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
9 17 23 8 16 4 3 42 2