Leucaena is a thornless, long-lived shrub or small tree with drooping, bipinnate leaves and clusters of globular, cream coloured inflorescences. It bears clusters of straight, flat, brown pods that are raised over the seeds. The species is of Mexican origin, but has become naturalized in most countries of the tropical world. It is widely utilized as a long-lived and highly nutritious forage tree and source of firewood, timber, human food, green manure and shade, as well as for erosion control.

In South Africa it seems not be utilized to its full potential, and in the absence of its natural enemies it is invading forest margins, roadsides, wasteland and riverbanks.

In terms of the Alien and Invasive Species Regulations (AIS), National Environmental Management: Biodiversity Act (Act No 10 of 2004), leucaena was listed as a category 2 species. A permit is therefore required to propagate, grow, sell or purchase it. Any specimens growing in riparian areas need to be controlled and, wherever possible, removed and destroyed. 

Research was carried out to find host-specific natural enemies that would destroy the seeds of leucaena or prevent them from being formed, without affecting those parts of the tree that could be utilized, viz its stems and leaves. The seed feeding beetle, Acanthoscelides macrophthalmus, was released in South Africa and establishment has been confirmed. Contact Dr Terrence Olckers at University of KwaZulu-Natal, E-Mail: olckerst@ukzn.ac.za, regarding this project.