Invasive ramie moth detected on Kauaʻi, targeting māmaki
A report to Kauaʻi Invasive Species Committee last month led to the collection of a single live ramie moth caterpillar, the first detection of the invasive pest on the Garden Isle.
This situation is being cooperatively managed by Hawai’i Department of Land and Natural Resources Division of Forestry and Wildlife, Kauaʻi Invasive Species Committee and Hawaiʻi Department of Agriculture and Biosecurity, with assistance from University of Hawaiʻi at Mānoa.
Ramie moth caterpillars are voracious feeders of māmaki leaves and quickly defoliate entire plants.
The invasive caterpillars will also feed on other endemic nettles such as maʻoloa and ōpuhe. This pest also poses a threat to native invertebrates such as the Kamehameha butterfly and native snails by competing for the same plants.
Ramie moth caterpillars can range in size from 1/16 of an inch up to 4 inches long and from green to yellow and black with bright orange-red spots and thin white hairs as they develop.
Adult moths are dark brown with black and silver markings on their wings. Their wingspans can reach 3.5 inches.
The first detection of this moth in Hawaiʻi was in 2018 on Maui. This was followed by a detection in 2020 on Hawaiʻi Island, with another in 2025 on Oʻahu.
Only a single caterpillar has been found on Kauaʻi thus far; however, officials ask the community to be on the lookout for others.
While eggs and caterpillars might move from island to island on host plants, it is possible for adults to disperse via flight and air currents.
Early detection of the ramie moth with help from residents is critical to prevent a rapid islandwide spread of the invasive insect into Kauaʻi’s native forests.
If you see a ramie moth or ramie moth caterpillar on māmaki or other host plants, take photos and report the sighting immediately to 643pest.org.
Ramie moth caterpillars might look similar to those of the Kamehameha butterfly. You can view comparison photos of the two species here.
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