Cambrian: Opinion

Ants don’t have to make gardeners cry, ‘Uncle!’

The Argentine ant feeds on honeydew excreted by insects such as these brown soft scales.
The Argentine ant feeds on honeydew excreted by insects such as these brown soft scales.

What’s crawling in your coastal garden?

Wildlife is everywhere this year. There is an abundance of food for all. From big four-legged animals to tiny pesky critters like ants; the garden is alive and well. Insects are busy at work feeding young ones, harvesting and storing, and alas, occasionally invading your home uninvited.

There are hundreds of different varieties of ants that hang out in and around our homes. Most varieties are quite harmless and even considered beneficial because they feed on fleas, termites, and other soft-bodied insects. The Argentine ant first invaded North America as a “stowaway” on coffee boats from South America.

The Argentine ant is the common variety that you see walking in a line, carrying bits of food that will help sustain its colony. If you’ve flooded an area that houses an underground ant nest, you’ll see them carrying small white eggs to safety. The Argentine ant loves sweets and sometimes proteins, lives in nests underground, is about  1/8 of an inch long and brown in color.

The Argentine ants are not native and are not considered beneficial. They protect plant pests like aphids, a “plant sucking” insect. They harvest the aphid “honeydew” (a sweet name for excrement) for food supply. Honeydew often leads to ugly, sooty mold you find on plants and even on outdoor furniture. Get rid of the Argentine ants and you get rid of “sooty mold”.

Trails of ants traveling up the stems of shrubs, tree trunks, and hummingbird feeders, can be treated safely with a product such as “Tanglefoot.” It’s a sticky substance applied to the stem or trunk of a tree or shrub that ants will not cross.

There are no magic tricks for removing Argentine ants from your property. You probably shouldn’t even try to eliminate them from your entire outdoor area. You’ll want to keep them out of the house for sanitary reasons and for your peace of mind. Exclude them by caulking holes and cracks in the foundation and wooden structures. Store food, especially sweets and protein like dog food, in airtight containers. Do not use insect sprays near food items. Wipe ants up with soapy water or diluted vinegar.

For reducing the number of outdoor Argentine ant colonies, use “baits.” Baits are the only tools recommended by Master Gardeners for managing ants. Bait contains poisons that are mixed with a bit of food that is taken back to the colony to be fed to larvae, and to the queen.

According to UC Pest Notes, “Several refillable bait stations are available including the Ant Café, Antopia, Ant-No-More and KM AntPro. The University of California research with the KM AntPro dispenser has shown that it can be effective when properly installed and maintained outside the home.”

With a little effort, we can keep critters, both large and small, at bay and enjoy our gardens and out-of-doors this summer. Keeping tiny pests like ants out of your home and off your plants will take a bit of patience and persistence, but it will make your summer so much happier.

Lee Oliphant’s quarterly column is special to The Cambrian. She shares her garden and chickens online at and Email her with gardening questions at

About master gardeners

Master Gardeners use research-based information to promote environmentally responsible and sustainable horticultural practices. For gardening questions, call 805-781-5939. Workshops on gardening are held on the third Saturday of each month at 10 a.m. to noon at 2156 Sierra Way, San Luis Obispo. Visit Master Gardeners at for details of happenings.