Abstract: A new larval host plant, Acacia dealbata Link (Mimosaceae), is recorded here for the Australian jewel beetle, Agrilus australasiae Laporte & Gory Coleoptera: Buprestidae: Agrilinae). Its larval/pupal chambers are described and known larval and adult host/food plants listed. The known larval host plants are all Acacia species, viz. A. dealbatas Link., A. pycnantha Benth. and A. sophorae (Labill.) R. Br. The adults are known to feed on the leaves of Acacia dealbata Link, A. decurrens (Wendl.) Willd., A. parramattensis Tindale and A. sophorae (Labill.) R. Br.