1996, a local outbreak of Tremex wood wasp was detected between Tamworth and
Sydney, N.S.W. Tremex is a Siricid wasp (related to Sirex) that attacks and
kills poplars and willows. It lays eggs in the bark and the larvae bore through the wood,
leaving characteristic emergence holes. A fungus associated with the wasp kills the trees.
It appears that the population in NSW has been there for 10-15 years.
Dieback symptoms in poplars caused by Tremex
Tremex looks similar to the Sirex wasp, but
has shorter antennae. The adult wasp is about 3 cm long. The colour is dark brown abdomen
with with yellow stripes (female only), reddish-brown wings and reddish brown head. Our
Agency has been asked by the Plant Health Committee (PHC) to undertake an ad hoc survey to
ascertain if Tremex is present in Western Australia.
Stump showing Tremex galleries
All surveillance staff are required to do at present is to
look for plantings of poplars or willows and mark down addresses or position of trees on a
street map. The best place to find grouped plantings of both species is usually in
municipal parks, gardens and around shire offices. Poplars are also grown in some farming
areas as windbreaks. If the tell tale dieback symptoms are noticed a closer inspection of
the tree is warranted to look for evidence of Tremex wasp activity.
Trunk with suspect Tremex emergence holes.