Lobate Lac Scale – A “Most Unwanted” Pest

Lobate lac scale (Paratachardina pseudolobata) was discovered on Oahu at Moanalua Gardens during the Hawaii Tree Climbing Championship the first weekend in October 2012. To the large gathering of arborists, it was obvious that something was wrong with a weeping banyan (Ficus benjamina) there. It had major dieback and the part that wasn’t dead was heavily covered in black. Trees of Hawaii, Inc. dropped off samples to Hawaii Department of Agriculture (HDOA) who identified it as lobate lac scale, a pest new to Hawaii. It had previously been known to occur only in Florida in the U.S. and was included in the Most Unwanted Pests in the United States poster compiled by Arnold Hara et al (CTAHR Publication IP-29, February 2011).

After receiving the sample, HDOA surveyed Moanalua Gardens and found lobate lac scale infesting the weeping banyan, Chinese banyan, red hibiscus, native white hibiscus, and mango. It has been found infesting a total of 17 plant species on Oahu so far. See below for a list. One of the concerns about this pest is its broad range of hosts. In the U.S., there are 200 known hosts. Worldwide, there are over 300 known hosts. No one knows where the pest originates. The black substance found on the tree is a sooty mold growing on the honeydew excreted by the lobate lac scale. Based on the amount of time for the pest’s life cycle and the different stages found at Moanalua Gardens, the infestation has been there for at least a year. The pest is well-established on Oahu and has so far been found in Moanalua, Pawaa, Pearl Harbor, Pearl City, and Punchbowl. Hibiscus and citrus are favorite host plants for this pest.

Arnold Hara, an ornamental entomologist for CTAHR, checked with Florida for recommended treatment methods of lobate lac scale. Merit drenches were effective there. Combining these with trunk sprays of Safari is also recommended, because Safari is more soluble and should give a quicker uptake but has a shorter residual than Merit. Doing other things to optimize plant health, like proper irrigation, mulching, and alleviating soil compaction around the plant, should help build the plant’s resistance to infestation. HDOA may consider biological control as a future option.

Darcy Oishi, Biological Control Section Chief of the HDOA Plant Pest Control Branch, has requested that if anyone finds these scales at any new locations, please let HDOA know right away. If you find this pest, please contact:

Email: hdoa.ppc@hawaii.gov
Oahu: 973-9525 (voice mail)
Leave your name and phone number and HDOA will call you back for more information.

Maui: 873-3555 (Mach Fukada)

Big Island – Hilo: 974-4146 (Patrick Conant)
Big Island – Kona: 323-7579 (Rob Curtiss)

Kauai – 274-3072 (Craig Kaneshige)

As for the weeping banyan where the pest was first found, Aloha Arborist Association (AAA) held a volunteer work day to prune off the dead wood and treat the tree on November 3, 2012. Unfortunately, the tree did not respond to treatment. With 75% of the crown dead in a high traffic area, the owner had the 100+ year old tree removed in January 2013.

Carol Kwan is the President of Carol Kwan Consulting, a Certified Arborist, and the Secretary of Aloha Arborist Association.  Mahalo to HDOA for its input and review of this article.

For more information from HDOA, click here.

Weeping banyan infested with lobate lac scale, Moanalua Gardens. Photo by Alvin Undan, Trees of Hawaii.

Koki’o ke’oke’o, native white hibiscus, infested with lobate lac scale. Photo by Walter Nagamine, HDOA.

Lobate lac scales on red hibiscus. Photo by Cheryl Young, HDOA.

Close up of adult female lobate lac scales. Photo by Walter Nagamine, HDOA.

Various life stages of lobate lac scales. Photo by Walter Nagamine, HDOA.

Close up of a red crawler, the first instar of a lobate lac scale. Photo by Water Nagamine, HDOA.