Old World climbing fern smothering vegetation

Old World climbing fern is a weed in some parts of the USA where it smothers vegetation.

Biological control of the Old World climbing fern in the USA

The USDA’s Australian Biological Control Laboratory is conducting biological control studies on Old World climbing fern which is a weed in the USA.

  • 28 January 2009 | Updated 14 October 2011

CSIRO and the United States Department of Agriculture are working together to control the spread of Old World climbing fern in the United States of America (USA).

The weed

The native range of the Old World climbing fern, Lygodium microphyllum, covers much of the moist old world tropics and subtropics from Africa to India, South-East Asia, Australia, and some Pacific islands.

It is found in a variety of habitats across its native range. In eastern Australia (Queensland and New South Wales) and in New Caledonia, it is common in the freshwater creeks and depressions of the coastal wetlands. It is often found growing with the Australian broadleaf paperbark, Melaleuca quinquenervia which is also a weed in the Everglades of Florida, USA.

Old World climbing fern climbing vegetatiion.

When growing in its native range, the Old World climbing fern does not form a smothering blanket.

Old World climbing fern has rapidly invaded southern Florida, particularly in moist environments, where it climbs over other plants, including tall trees, forming massive walls of vegetation. It also forms thick mats on the ground that smother native plants.

Infestations of the climbing fern can help spread fires as flames can be carried rapidly to the tops of trees by the burning fern and then spread by floating pieces.

The range of L. microphyllum is predicted to expand into central Florida and large parts of the tropical areas in the Americas.

Biological control

L. microphyllum is considered to be a good target for biological control for several reasons:

  • it belongs to a taxonomically isolated group, not closely related to native or economic plants in Florida
  • it is not known to be a weed in its native range
  • non-biological control methods are environmentally damaging and too expensive to use on the scale required to control the weed.

Scientists at the United States Department of Agriculture's (USDA’s) Australian Biological Control Laboratory (ABCL) in Brisbane, Queensland, Australia, have been searching for potential biocontrol agents in Australia. Three have undergone specificity testing and have been approved for release in the USA.

Three biocontrol agents have recently been released on Old World climbing fern in the USA.

The defoliating pyralid moth, Austromusotima camptozonale, was released in Florida in 2005 but it is not yet known if the agent has established.

A gall-forming eriophyid mite, Floracarus perrepae, was approved for release in January 2007. This mite deforms the growth of L. microphyllum and causes leaf necrosis.

A second defoliating moth, Neomusotima conspurcatalis, was released in 2008 and has established at a small number of sites where it is causing substantial defoliation. A defoliating sawfly, Neostrombocerus albicomus, is being evaluated in quarantine in Florida.

Future research

Future research will focus on several species of stem-boring moths which damage L. microphyllum in:

  • Hong Kong
  • Singapore
  • Thailand.

Rearing protocols are being developed before host testing can commence.


The Australian Biological Control Laboratory (ABCL) is hosted by the CSIRO laboratories at Long Pocket in Brisbane, Queensland, Australia. It is operated by the United States Department of Agriculture, Agricultural Research Service (USDA-ARS).

Find out more about The US Department of Agriculture’s Australian Biological Control Laboratory.