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Cuban Laurel Thrips - fact sheet
Cuban Laurel Thrips (Gynaikothrips ficorum), native insects of the tropics, can be severe and debilitating pests of ornamental fig trees. They attack some figs particularly badly, such as the Cuban Laurel (Ficus retusa), the Weeping Fig (Ficus benjamina) and the Hills Fig (Ficus microcarpa var. hillii), resulting in severe deformation of leaves and subsequent defoliation. From a horticultural point of view this renders the tree aesthetically unpleasing. The deformed leaf also has greatly reduced photosynthetic capacity. These thrips have the potential to devastate many streetscapes in Australia - e.g. in the Sydney CBD where the Hills Fig is predominant.
Thrips life cycle
On hatching from the egg, young thrips feed along the midvein on the upper surfaces of young tender fig leaves. As they feed their mouthparts damage the leaf surface by puncturing it and producing purple-coloured pits in the leaf tissue. The leaf folds or curls, producing a shelter for the young thrips. Subsequent generations of thrips continue to live in the same shelter until the leaf eventually dies. Leaves that have been severely attacked become tough, yellow and leathery before falling from the tree.
Eggs and juvenile thrips are pale coloured, whereas adults are black. Adult Cuban Laurel Thrips are around 1 mm in length. They lay their eggs on the upper surface of curled leaves. There may be four or more generations per year, and if temperatures are favourably high, the Cuban Laurel Thrips can complete a generation in thirty days from egg-lay to adult. The adult is winged. It is a fast, strong flier, and will migrate in hot weather.
Chemical control: There are no current recommendations for the use of chemicals against these thrips in Australia.
Biological control: Three species of predatory bugs have been used to control these thrips in North America. These are Macrotrachiella laevis and Cardiastethus rugicollis in Puerto Rico, and Montandoniola moraguesi in Florida, USA. Another species of predatory bug, Orius insidiosus, which underwent a trial in a large indoor situation in the USA, was not successful in controlling the thrips to any great degree. None of these insects are present in Australia.
Cultural control: Tip pruning of infested plants will remove the food source of the thrips and also any thrips and eggs that may be present on these new shoots. This is obviously impractical where large numbers of mature trees are involved, such as in a municipal park.