Saunders' case moth

Introduction

The caterpillars who make their own mobile home are often seen attached to fences and walls in urban settings.

Case moths, bag moths or bagworms are names given to a group of moths whose caterpillars make mobile homes from silk, usually attaching plant material, detritus or sand grains to the outside.

The Saunders' case moth first attaches leaves then short twigs arranged lengthwise.

Identification

• The adult males have black wings, an orange hairy head, and a black and orange banded abdomen.
• Female adults have no wings and remain in the larval case. They are white with a brown head and reach a length of about 30 mm.
• Caterpillars of each species build quite distinctive cases, although there can be considerable variation within a single species, especially in those that feed on a wide variety of different plants.
• Case moths spend most of their lives as caterpillars, the larval stage, which may last for up to 1 or 2 years in some species. Once constructed, the female caterpillars never leave their cases.
• The head and thorax of the caterpillars are quite heavily armoured and they have 3 strong pairs of legs on the thorax with which they move around, dragging the case behind them.
• The case has two openings, a larger ‘mouth’ through which the caterpillar protrudes its head and thorax to feed and move, and a smaller hole at the other end through which the droppings are ejected.

Distribution

Eastern Australian states and territories.

Habitat

Terrestrial.

Feeding and diet

Many species of case moth caterpillars are plant feeders; others feed on lichens; while some live within the nests of ants and are thought to be scavengers.

Other behaviours and adaptations

The caterpillar is a very skilled climber, able to climb any surface by building a silk ladder attached to the surface they wish to climb.

Life history cycle

• Pupation can be a few weeks to a few months depending on the season and the weather.
• The female adult has no wings and so remains in the case.
• The male has short wings and a long abdomen.

Breeding behaviours

The adult males long abdomen enables it to breed with the female who remains inside her case.

Dangers to humans

None.