Little Fire Ant (Wasmannia auropunctata)
Since the discovery of Wasmannia auropunctata on the Hawai‘i Island in 1999, the Hawai‘i Department of Agriculture worked closely with the local invasive species committees (including OISC), as well as the United States Fish and Wildlife Service to prevent the further spread of this ant species. The Hawai‘i Ant Lab, a project of the Pacific Cooperative Studies Unit, is also working diligently to mitigate the threats and prevent the inter-island and intra-island spread of existing invasive ant species, including the little fire ant.
- This ant is orange-red to light brown in color, all workers are 1.5 mm in length (half the size of a sesame seed, or as long as a penny is thick, about 1/16 “)
- Slow-moving, easily dislodged from leaves, plants, and trees
- Prefers moist conditions, forming colonies on the ground AND in trees
- Native to Central and South America, LFA were accidentally introduced as hitchhikers on imported plants
- Delivers a painful sting when disturbed. Welts can last for weeks
- Infests agricultural fields and farms, where they damage crops and sting workers
- Promotes plant pests such as aphids, white flies and scale insects, which secrete plant sap that the ants eat. In turn, the ants protect these insects from natural predators and parasites.
- Easily blown out of trees, stinging when they get are caught in hair or clothing.
- Infests homes, beds, furniture and food
- Has been linked to corneal clouding and blindness in pets
- In the Galapagos, LFA eat tortoise hatchlings and attacks the eyes of adult tortoises
- Infest bee hives, preying on the larvae and eventually destroy the hive.
- Large infestations are difficult and expensive to control
- LFA “farm” agricultural pests such as scale insects and mealy bugs for their sugary excrement as an alternate energy source. LFA protect these pest from farm-friendly predators like ladybirds ( AKA ladybugs). The scale insects and mealy bugs cause substantial reductions in crop health and production.
- First detected on O’ahu in December 2013 in a shipment of hapuu logs from Hawaii Island.
- Early detection and prevention are essential and the public is urged to report unusual ants to 643-PEST.
- On December 13, 2018, a resident on Alokahi St. contacted HDOA to inquire about ants in her home. On December 19th, staff from HAL retrieved the ant samples which were identified as LFA on December 20th by an HDOA entomologist. On December 21st, HDOA and HAL staff returned to the home and conducted a survey of the exterior of the residence and detected LFA in the patio, carport and along the perimeter of the property. Staff returned on December 24th to survey two surrounding properties which also had LFA. A larger survey of 12 properties in the area was conducted on January 4th and LFA was found in seven of those properties. On January 9th, another survey of two additional properties was conducted and one was found to have LFA. According to the treatment plan developed by HAL researchers, several types of pesticides and bait formulas are applied on a six-week interval for a total of eight treatments. Monitoring of the area will continue for several years.
- A total of 11 properties covering about two acres were treated on January 24th, 2019, including a 15-meter buffer zone around the infestation area. The area will undergo the treatment plan developed by HAL researchers, several types of pesticides and bait formulas are applied on a six-week interval for a total of eight treatments. Monitoring of the area will continue for several years.
- Two infestation sites were found in April 2014 and June 2014 in Waimānalo and Mililani-Mauka, respectfully.
- Waimānalo, April 2014- LFA were detected on an abandoned lot in Waimānalo. Based on the size, the infestation was likely present for several years before its detection. The area was treated for one year and moved into a monitoring phase. During the monitoring phase, LFA were found to still be present in a single, large tree. The tree and immediate surrounding area are undergoing treatments and the rest of the area is continuing to be monitored regularly.
- Mililani-Mauka, June 2014- Thanks to the actions of residents sampling and submitting suspicious ants, an area of about 20 adjoining properties and a green space were found to be infested with little fire ants. Residents were all cooperative in allowing HDOA, Hawai‘i Ant Lab, and OISC to conduct surveys and treatments, as well as assisting in clearing trails in the green space for treatments. After one year of treatments, no LFA have been detected and the area moved into the monitoring phase. There continue to be no LFA detected in the post-treatment phase and monitoring will continue for at least three years to ensure successful eradication.
- OISC partners with HDOA in early detection surveys of garden centers and nurseries on O‘ahu, as well as public outreach activities to raise awareness about LFA.
- OISC’s management goal for little fire ant is island-wide detection and control.
How can you help? Collect and submit ants for identification at least once a year.
LFA are well-established on Hawai‘i island and hitchhiking ants pose a real threat…and ants are expert hitchhikers! But keep in mind that small infestations can be eradicated, which is why early detection is extremely important in keeping O‘ahu LFA free.
Testing is easy! Just peanut butter and some chopsticks…the cheaper the peanut butter, the better!
- Smear a thin coat of peanut butter on one end of a disposable chopstick or popsicle stick. (A thick coat is no more attractive to ants and only makes identification more difficult). If you are allergic to peanuts, use small pieces of luncheon meat and tongs to retrieve the pieces.
- Place sticks in shady areas in, around, and on plants, including potted plants. For a thorough survey, place at least three sticks per plant, and/or one stick every two feet. Leave the sticks out for 45 minutes to 1 hour.
- Carefully pick up the sticks (so the ants don’t fall off!), and seal them in a plastic bag. Write your name, contact number, and the date on the bag and freeze for 24 hours to kill the ants. An address is helpful, but not required.
- Just because you have ants, doesn’t mean they are little fire ants. Some ants are look-a-likes and require an expert to identify them. Turn in ALL ant samples for identification and peace of mind.
You can mail your ant samples to either:
Hawaii Deptartment of Agriculture
1428 S. King Street
Honolulu, HI 96814
Oahu Invasive Species Committee
743 Ulukahiki Street
Kailua, HI 96734
Pest Alerts and Publications:
- Little fire ant brochure
- “Little Fire Ants in Hawai’i” A documentary by Maui Invasive Species Committee
- Impacts of little fire ant stings
- Little fire ant updates from Hawaii Invasive Species Council
For more information, see:
- “How to Test for Little Fire Ant” video
- Spot the Ant. Stop the Ant
- The Hawai’i Ant Lab
- Hawaii Department of Agriculture; Plant Industry Division