Corn Ear Worm, Tomato Grub, Tobacco Budworm, Cotton Bollworm
(one synonym : Heliothis conferta Walker, 1857)
HELIOTHINAE , NOCTUIDAE , NOCTUOIDEA
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:
but it is a serious pest internationally on various crops, including :
as well as ornamental plants and flowers, including:
The specimen pictured above was actually found on :
purchased from a supermarket in Bundaberg.
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 delicate darker tracery around a single dark mark on each wing. The hind wings are buff with a dark border which contains a light patch. The chemical identities of the sex attractant compounds for this moth (pheromones) have been elucidated.
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. The adults fly long distances, and these have been tracked by radar.
The adult moths look very similar to those of the related species in the same genus : Helicoverpa punctigera. However, for Helicoverpa armigera
The species is a pest world-wide:
and all of Australia, including
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 (yet) seem to have appeared in the Americas. 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).
Unlike its relative: Heliocoverpa punctigera, it develops resistance to many insecticides. Attempts are being made to control the Caterpillar using :
Further reading :
Ian F.B. Common,
Moths of Australia,
Melbourne University Press, 1990, fig. 50.8, pp. 49, 64, 468.
Heliothine Moths of Australia: A Guide to Pest Bollworms and Related Noctuid Groups,
CSIRO Publishing, Melbourne 1999.
Paul Zborowski and Ted Edwards,
A Guide to Australian Moths,
CSIRO Publishing, 2007, p. 198.
(updated 15 April 2013)