Biological control agents are observed on Mimosa pigra six and 12 years after their release in the Northern Territory, Australia.

Two biological control agents (a rust and a seed feeder) released to assist with control of Mimosa pigra (mimosa) in the mid 1990s. Both agents, based on 1990s surveys were believed to have failed to establish. However, recent (dates) surveys have shown that both agents did in fact establish and are now having an effect on mimosa. These findings highlight the importance of long term monitoring when evaluating an agent’s establishment and spread. We discuss the implications of our findings for future biological control programs.