THE TARGET: HALA SCALE (HEMIPTERA: HALIMOCOCCIDAE)

Hala Scale is an Invasive Insect
The Hala tree is iconic in Hawai’i and one of the most important plants in native Hawaiian culture. It continues to be threatened by the invasive Hala Scale insect, which causes significant damage to the plant. The Hala Scale can cause leaf deformities, discoloration, stunting, twisting, yellowing, and leaf blade length can be greatly reduced, all of which render leaves useless for weavers.
The insect attacks the tree’s fruit and kill young seedlings. Eventually Hala Scales can cause entire crowns of the plant to fall off, and the insect can cause premature death of the tree. These attacks on the fruit and seedlings also prevent new trees from regenerating current Hala stands.
There is a significant concern that the remaining Hala trees will be the last, as the infestation of the Hala Scale puts these ecosystems at risk of disappearing and being replaced by invasive species.
Distribution:
- Hala scale was originally found on Maui in 1995 and spread to Molokai. There was a small infestation treated by the Hawai’i Department of Agriculture (HDOA) on O’ahu in 2013. Hala Scale has not yet spread to Hawai’i island or Kauai.
What you can do: If you see this species, call 643-PEST and/or visit 643pest.org.

THE CANDIDATE: To Be Determined

No candidate has yet been identified. However, staff from the University of Hawai’i advise that in places like Southeast Asia (Singapore, Thailand, Indonesia, and Malaysia), Hala Scale is not a major pest most likely because natural enemies and biocontrol agents are keeping the insect in check. Potentially, its hoped, that there is a Southeast Asian biocontrol agent that can be used in Hawai’i to keep Hala Scale in check. Citation)
- Its imperative to ensure biocontrol agents are very specific to the problem pest. Regulations for bringing biocontrol agents into Hawaiʻi are much more strict than mainland U.S. policies. (Citation).
There are many predators of “scale” species already established in Hawaii, especially Coccinellids or Lady Bugs, and some of them focus on Hala Scale. Another potential agent includes tiny wasps that may parasitize adult scales and eggs, but the challenge is that they dislike salt air and windy conditions present in Hala habitat. (Citation)
HDOA states that it is looking into exploring biological control agents for Hala Scale as biocontrol is now Hawai’i’s last option to save the remaining culturally important Hawaiian Hala stands. (Citation).

The Hawai’i Department of Agriculture stated it may be releasing a report on a potential biocontrol agent in February 2024.