Mnesampela privata

Mnesampela privata (Guenée, 1857)
(one synonym is : Azelina inordinata)
Autumn Gum Moth
NACOPHORINI , ENNOMINAE , GEOMETRIDAE

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

Mnesampela privata
Array of eggs recently hatched.

The Caterpillars start life as one of an array of 50 or so pale green eggs laid in neat rows glued on a leaf of a food plant.

The early instars of this Caterpillar are pale green with dark markings and brown heads.

Later they become dark grey-green. However, all stages have a conspicuous pair of yellow knobs on the second abdominal segment. A double row of brick-red dots marks the back, one pair of dots per segment. The Caterpillars have four pairs of ventral prolegs, with the front pair slightly smaller than the others. When threatened, the Caterpillars adopt a posture with the head curled around toward the tail.

Caterpillars in defensive posture.
(Photo: courtesy of Merlin Crossley)

They feed on the foliage in young shoots of various Gum Trees ( Eucalyptus, MYRTACEAE ) including :

Red River Gum ( Eucalyptus camaldulensis ),

Tasmanian Blue Gum ( Eucalyptus globulus ),

Rose Gum ( Eucalyptus grandis ), and

Mottlecah ( Eucalyptus macrocarpa ).

Initially the Caterpillars feed in a group, eating only the surface flesh of the leaves. Later instars hide during the day in a communal shelter. For this, they use a curled dying leaf, still attached to the stem. The Caterpillars leave this nest at night to feed. For feeding, a Caterpillar will lie along the edge of a leaf, and feed from the edge inwards.

Caterpillar in feeding posture
(Photo: courtesy of Merlin Crossley)

The Caterpillars grow to a length of about 3 cms. They pupate in individual cells in the soil. The pupal stage can last for eight months.

(Photo: courtesy of Merlin Crossley)

The adult moths have light brown fore wings with patches of reddish brown, especially along the inner margin, and to a lesser extent around the base. The hind wings vary from yellow to orange. The fore wings have slightly recurved tips, and the hind wings have scalloped edges. The underside of each fore wing has a conspicuous black submarginal streak at the apex. The moths have a wingspan of about 4 cms.

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

The pheromones of this species have been investigated.

The species is found over most of Australia. It is a pest in forests in

Queensland,

New South Wales,

Australian Capital Territory,

Victoria,

Tasmania,

South Australia, and

Western Australia.

underside
(Photo: courtesy of CSIRO Entomology)

Attacks seem to worse in plantation environments with reduced tree species variety. Research has been conducted on control :

by Rod Griffin using egg mass counts,

by Dr Richard Milner using fungal pathogens, and

by Ros Schumacher using natural parasitoids of the species, including :

Heteropelma scaposum ( ICHNEUMONIDAE ),

Pristiceros species ( ICHNEUMONIDAE ),

Neolevansa species ( ICHNEUMONIDAE ), and

Eriborus species ( ICHNEUMONIDAE ).

These Caterpillars have been found regularly every June on a particular Mottlecah tree in a Melbourne suburb. The tree appears to be none the worse for these attacks.