Eucalyptus cossid moth

Eucalyptus cossid moth
Coryphodema trisitis

Coryphodema capensis (Felder, 1874), Coryphodema punctulate (Walker, 1856), Phalaena (Noctua) tristis (Drury, 1782), Coryphodema capensis (Felder, 1874), Brachionycha punctulata (Walker, 1856), Cossus seineri (Grünberg, 1910), Cossus streineri (Dalla Torre, 1923)

Wood boring

Round holes penetrating the sapwood.

Trunk and branches of infested trees turn black.

Resin and sawdust appear on trunks and branches.

Extensive tunnelling of larvae is found in the sapwood and heartwood.

Pupal casings protrude from emergence holes or can be found on the forest floor.

Sawdust is found at the bases of trees.

 

The eggs are approx. 1mm long, oval in shape and dull cream coloured. Larvae are approx. 30-40mm long when fully grown. Fully grown larvae have a brown head and the body is light yellowish in colour with reddish blotches. Three short pairs of legs are present behind the head. Larvae pupate in woven silk and sawdust cocoons. Pupae are about 25-35mm long, with rows of spines present on the abdomen and the head terminating in a spine. The adult is rarely seen in the field. It is short lived (about one week) with a wingspan of 25-50mm. Body is greyish brown, front wings are mottled brown and hind wings are mottled light grey. 

 

Adult female cossid moths lay eggs on the bark of trees, usually in a sheltered place such as cracks in the bark. Upon emergence, larvae bore through bark and feed on the cambium. As the larvae grow, they bore into the wood, where they cause extensive tunneling. Pupation occurs in pupal cocoons constructed inside the larval tunnels. Just prior to adult emergence, the pupae cut themselves out of the cocoons and wriggle towards the tunnel openings until their bodies project halfway out the tree. In this position the adults emerge from the pupal cases, resulting in the shed pupal cases protruding half way out the tree or falling to the ground. The cossid moth has a two-year life cycle with adult emergence in September to December.

Larvae feeding in the cambium and the extensive tunneling in the sapwood and heartwood results in severe damage to trees and makes them prone to wind fall. Tree mortality in stands can exceed 80 %. Both the main trunks and branches are attacked. Trees from five to fourteen years old have been infested, but it is likely that the cossid will infest both younger and older trees, provided the diameters of the trunks/branches are sufficient to enable the larvae to feed. 

 

1872 (Drury 1872, Pettey 1917)
KwaZulu-Natal, Mpumalanga, Western Cape
native in South Africa

Gallery

Frass and sawdust from larval tunneling
Eggs laid on bark
Larvae boring in wood
Adult moth
Adult male (left) and female (right)