Test your yard to prevent the spread of little fire ants

Little fire ants are stinging insects that threaten public health, pets, agriculture and native species. So many of us have stories about being stung by a different type of ant, tropical fire ants, when we’ve stood in the wrong spot at a picnic or at the beach park, but these little fire ants (Wasmannia auropunctata) are different.

Little fire ants prefer to live on plants and in trees in moist, shady spots, where they can rain down on people and sting them.

On the Big Island they have become widespread from Puna to Hama­kua. Since their discovery in Puna in 1999, they have caused incredible damage.

Some locations have infestations of 244 million ants per hectare. For the typical house lot of 5,000 square feet, this would mean sharing your property with about 11 million ants. In infested areas, officials are seeing pets and livestock with skin rashes and blindness from being stung.

Agricultural workers are being constantly stung in infested areas, and even birds have been attacked in their nests.

For some time, efforts focused on keeping the ant from spreading from the Big Island, but in December the state Department of Agriculture confirmed that little fire ants had been moved to Oahu, Maui and Lanai, hidden in tree fern logs sold at major garden shops and some nurseries.

On Maui just one log was found to have little fire ants, and surveys at nurseries and landscapes across the island have resulted in no new reports.

On Oahu the Agriculture Department traced logs to 10 nurseries and landscapes, and they have treated the known infestations. However, it is estimated that more than 1,000 logs have not been accounted for, some of which may have been infested. Agriculture inspectors at interisland ports continue to intercept little fire ants in plants, cut flowers, foliage like ti leaves and other materials shipped from infested areas.

The Agriculture Department needs to know the extent of the little fire ants’ spread to other islands and locations of infestations so that they can be controlled before it is too late. Your help is needed.

Test your property for little fire ants:

1. Place chopsticks with a slight smear of peanut butter every few feet in and around plants, in yards, gardens and nurseries (using too much peanut butter makes it difficult to identify the ants). Little fire ants particularly like shady, moist areas, such as the bottoms of pots and banana leaf axles.

2. Leave the chopsticks for about an hour during the day.

3. Check all chopsticks. If the ants you see are black, or fast-moving, more than one color, or if some of them have heads that are much larger than their bodies, they are not little fire ants.

4. If you are unsure about the ants, or if you find orange ants that are very small, you may have little fire ants, but a positive identification will require help. Place the chopstick with ants into a zip-top bag, label it with your contact information and place it in the freezer overnight to kill the ants.

5. Call the Hawaii Department of Agriculture pest hotline at 643-PEST (643-7378) to make a report and get help, or drop off the sample at any Department of Agriculture office. Do not move or spray infested materials, and do not move live ants!

Ants are a very difficult species to control, but together we can do it.

For more information, how to test your yard and a video on the ants, visit the University of Hawaii Master Gardener website at www.ctahr.hawaii.edu/uhmg.

Christy Martin leads the Coordinating Group on Alien Species. Jayme Grzebik, urban horticulturist on Oahu with the University of Hawaii Cooperative Extension Service, can be reached at grzebik@hawaii.edu.