Case
Moths: What are these strange objects?
They are the protective envelopes of case moths. There are about 25
species of this interesting group of insects in Australia. Their caterpillars
make portable protective cases of very strong silk. On the exterior of this
case they cleverly weave sticks and leaves. The cases have two openings. The
opening at the top is for feeding and the opening at the base for waste
product disposal and eventual exit of the mature moth.
Before pupation, the caterpillar turns around and faces the bottom of the
case. At maturity the pupa shell is pushed partially out of the case. Remnants
of the pupa shell may be seen at the bottom of both illustrated cases.
At Yallaroo some plants become covered with cases. A Grevillea is
particularly favoured. The case moth caterpillars do strip a number of leaves
from the plant but cause no long lasting damage. We adopt our usual attitude
to the wildlife at Yallaroo: “live and let live”. The case on the right
was taken from the Grevillea. The one on the left was harvested from an
Acacia. At the bottom of this case the caterpillar had incorporated
some Acacia buds.
We assume that the cases were constructed by the same species of moth,
although different materials were used in construction. The cases are the same
size and shape. The remnants of the pupa shell are the same size, shape and
have the same colouring.
Case moths belong to the family Psychidae.