Caterpillars

Caterpillars are the larval stage of moths and butterflies (order Lepidoptera). They vary enormously in appearance, but most are soft-bodied, cylindrical, and range from 10mm to over 50mm long depending on species and age. Colours span green, brown, grey and black, often with stripes, spots or a hairy covering. Some, like loopers, move with a distinctive arching motion because they lack a full set of middle legs. Adults are winged moths or butterflies that don't feed on the plant directly but lay the eggs that hatch into the damaging larvae. Eggs are usually laid on leaves, stems or in soil near the base of plants, singly or in clusters.

In gardens and lawns across Australia, caterpillars target a huge range of hosts: vegetables (cabbage, tomato, beans), fruit trees, ornamentals, and turf grasses. Many species overwinter as pupae in soil or leaf litter and emerge as adults in spring, with peak larval activity through spring and summer when warm, humid conditions favour rapid growth and multiple generations. Some, like armyworm and webworm in lawns, can build up quickly after warm, wet spells or following rain that follows a dry period.

Management relies on regular monitoring rather than routine treatment, since natural predators (birds, wasps, and predatory insects) often keep populations in check. Hand-picking is practical for small infestations on vegetables and ornamentals. Encouraging beneficial insects, rotating crops, and removing plant debris where pupae shelter all reduce ongoing pressure. Where numbers are damaging, targeted treatment while larvae are small is far more effective than waiting until they are large and heavily fed.

Correct identification matters because control timing and method differ between species — a leafroller curling foliage needs a different approach to a lawn armyworm feeding at night.