Helicoverpa armigera

Helicoverpa armigera (Hübner, 1805)
Corn Earworm, Tomato Grub, Tobacco Budworm, Cotton Bollworm
(one synonym : Heliothis conferta Walker, 1857)
HELIOTHINAE, NOCTUIDAE, NOCTUOIDEA

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

This Caterpillar is initially pale green, sometimes with black dots, and a pattern of thin dark lines running along the body, the lines being darker around the second and third segments.

In later instars , the dark lines become less conspicuous, and the black spots develop red areas around them.

There is a good deal of variation in colour in this species. Lighter and darker forms of both caterpillars and moths are known, for example, having white instead of black spots on the caterpillars.

The caterpillar has posture when disturbed characteristic of a number of species in this family : it lifts its head and curls it under the front of the body. If even more disturbed, it lets go and drops, rolling into a spiral.

In the wild, it has been found on:

Annual Sowthistle ( Sonchus oleraceus, ASTERACEAE ),

but it is a serious pest internationally on various crops, including :

Sunflowers ( Helianthus annuus, ASTERACEAE ),

Zucchini ( Cucurbita pepo, CUCURBITACEAE )

Beans ( Phaseolus vulgaris, FABACEAE ),

Leeks ( Allium porrum, LILIACEAE ),

Cotton ( Gossypium hirsutum, MALVACEAE ),

Maize ( Zea mays, POACEAE ),

Plum ( Prunus domestica, ROSACEAE ),

Lemon ( Citrus limon, RUTACEAE ), and

Tomatoes ( Lycopersicum esculentum, SOLANACEAE ),

as well as ornamental plants and flowers, including:

Pinks ( Dianthus, CARYOPHYLLACEAE ),

Geranium ( Pelargonium x zonale, GERANIACEAE ).

One specimen pictured above was actually found on :

Lettuce ( Lactuca sativa, ASTERACEAE )

purchased from a supermarket in Bundaberg.

close-upm of head and thorax
(Photo: courtesy of David Akers, Won Wron, Victoria)

When fully grown (4 cms.) it pupates in a cocoon under the soil.

The adult moth emerges after between three weeks (summer) and six months (winter). It has brown forewings with a variable delicate darker tracery around a single dark mark on each wing. The hindwings are buff with a dark border which contains a pale patch.

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

The undersides are buff with dark submarginal bands on each wing, and each fore wing also has a black comma mark and a black full stop.

underside
(Specimen: courtesy of the Macleay Museum, University of Sydney)

The adult moths look very similar to those of the related species in the same genus : Helicoverpa punctigera. However, for Helicoverpa armigera :

the caterpillars have white hairs on the prothorax,

the caterpillars have dark triangles on the first abdominal segment, and

the moths have a pale mark in the black border of the hindwing.

Tuvalu, 1991

The adults fly long distances, and these have been tracked by radar.
The species is a pest over much of the world :

South America, including:

Brazil,

Africa, including:

Botswana,
South Africa,

Europe, including:

Austria,
Spain,
United Kingdom,

Asia, including:

India,
Japan,
Java,
Pakistan,

Australasia, including:

New Zealand,
and most of Australia, including

Northern Territory,
Queensland,
Norfolk Island,
New South Wales,
Australian Capital Territory,
Victoria,
Tasmania,
South Australia, and
Western Australia.

In Europe, this species is often called the "Scarce Bordered Straw", but this name seems inappropriate in Australia where the caterpillar is so common. Note that the species does not seem to be established in the North America. In Australia, it is seldom found as far south as Melbourne. However, we regularly find it in Melbourne in ears of corn purchased from a greengrocer (that are presumably grown further north).

The pheromones of this species have been identified.

Unlike its relative: Heliocoverpa punctigera, this species develops resistance to many insecticides.
Attempts are being made to control the caterpillar using :

pheromone lures,

special chemicals such as Larvin (a combined ovicide and larvicide),

insecticides such as Fenvalerate synergised with Piperonyl Butoxide,

extracts from Neem tree ( Azadirachta indica, MELIACEAE ),

a Cypovirus ( REOVIRIDAE ),

a Granulovirus ( BACULOVIRIDAE ),

a Stunt Virus ( TETRAVIRIDAE ),

a Poxvirus ( POXVIRIDAE ),

extracts of the bacterium Bacillus thuringiensis ( BACILLACEAE ),

with Nematodes ( NEMATA ),

the caterpillar parasitoid wasp Microplitis croceipes ( BRACONIDAE ),

an egg parasitoid wasp Trichogramma species ( TRICHOGRAMMATIDAE ),