In early January, Richard Smith reached out to the Maui Invasive Species Committee (MISC), concerned about his avocado tree. “The leaves were turning black and brown, and when I turned them over, I could see these black bug-looking things covering them.”, the Wailea resident explained to staff. “I wasn’t sure what it was- or what I could do to save my tree- so I decided to report it.” Smith sent in photos and the MISC early detection team and entomologists at the Hawaiʻi Department of Agriculture (HDOA) quickly identified the insects as avocado lace bug.
First discovered in 2019 on central O’ahu, the avocado lace bug (ALB) quickly spread throughout the Gathering Island. Shortly thereafter reports came in from Hawai’i Island, Kaua’i, and Maui. Known from Central and South America, the Caribbean, Southeastern United States, and California, ALB is presumed to have arrived in Hawai’i on the leaves of an infested host plant.
“Avocado lace bug probably affects almost every tree on O’ahu to some degree and has spread across the entire island. It is also now well established on Hawai’i Island, and is spreading across Kaua’i and Maui,” said Janis Matsunaga, an entomologist with the HDOA Plant Pest Control Branch. “This has been one of the fastest spreading pests to invade Hawai’i in recent years,” Matsunaga added. On Maui, infestations are concentrated at lower elevations, however, they have been detected as high as Copp Road in upper Kula. There have been no reports of ALB on Molokai or Lānaʻi at the time of publication.
ALB does not directly impact the buttery fruit beloved as a Superbowl Sunday staple or as a topping on trendy millennial toast. Instead, it weakens the plant by sucking the sap from the undersides of avocado leaves, resulting in yellow blotches or browning and leaves falling prematurely. If you have an extensive infestation, the tree can lose so many leaves that it can’t photosynthesize and will put the plant under stress. The lack of shade that the leaves provide can also cause the fruit to sunburn. California farmers report reduced crop yields with large infestations, however, permanent impacts are rare; even trees that sustain severe damage have been able to recover the following fruiting season- a glimmer of hope for Hawaii farmers and backyard growers.
The bugs themselves are tiny. “They are about 1/16 inches long and have black and yellow bodies with a thick horizontal stripe against their lace-patterned wings, where they get the second part of their name. Immature avocado lace bugs are much smaller in size and are black” Matsunaga says. Another clue is black dots amongst the colonies, which are fecal matter and eggs cased in excrement.
The University of Hawaiʻi College of Tropical Agriculture and Human Resources (CTAHR) is determining the best treatment methods for avocado lace bug in our islands. They encourage limiting chemical applications to when infestations are high, and timing applications to avoid spraying when trees are flowering to protect beneficial insects like honeybees. Trials are also underway in determining particular avocado varieties that are more resistant to avocado lace bug than others. For backyard gardeners that discover a light infestation of ALB and want to treat it, CTAHR recommends using insecticidal soaps to control this pest. For further information and control, visit CTAHR’s website at ctahr.hawaii.edu.
In reporting this pest, Richard Smith was concerned that his avocado lace bug infestation would lead to him losing his beloved avocado tree, echoing the concern of many Hawaiʻi residents. Being vigilant by observing what’s happening in your backyard, reporting something new (such as to MISC or 643pest.org), and catching infestations early, it is likely that Smithʻs tree- and many others in our islands- will survive and continue to produce this delicious fruit.
Serena Fukushima is the public relations and education specialist for the Maui Invasive Species Committee. She holds a bachelor’s degree in environmental studies and a graduate degree in education from the University of Hawaii at Manoa. “Kia’i Moku, Guarding the Island” is written by the Maui Invasive Species Committee to provide information on protecting the island from invasive plants and animals that threaten our islands’ environment, economy and quality of life.
This article was originally published in the Maui News on February 12, 2022 as part of the Kia‘i Moku Column from the Maui Invasive Species Committee.
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