Every season we have an “adventure” with a new tropical bug or rodent that we have not encountered before. Recently, a new type of huge ant showed up on the walls and carpet. We are used to dealing with thick trails of ants emerging through a crack from the outside or running up a wall to food or some other attraction. But these ants had no interaction with each other and they appeared in strange places, like at the bottom of our coffee cup. Every day the number of roaming ants increased around the house. One day we found a dozen big ants floating in the water reservoir of our coffee maker and discovered a nest in the electrical compartment. The ant baits we regularly use to control other ants, have no effect on these huge ants. Spraying Febreeze, which we have found to be a deterrent to many bugs, in particular the millipedes that invaded us last summer, also have no effect.
Our quarterly bug spraying, which we were hoping would get rid of the giant ants, began an all-out ant invasion. A few hours after the spraying, the ants started coming out everywhere. They crawled up out of the thick wool carpet in the living room by the dozens and ran up the walls. Some were winged and flew upstairs. For days we wiped ants off the floor and vacuumed them off the rug. Every morning, while making morning coffee, we squished dozens on the kitchen floor. Since they never bit us, we could joke about them carrying us away.
After some research, we identified them as Hawaiian Carpenter Ants (Camponotus variegates). Though carpenter ants on the mainland can cause as much damage as termites, Hawaiian carpenter ants do very little damage to wood. They just like living in wood, usually outside in tree stumps and rotting wood, but they are happy to make nests in crevices, cabinets, cardboard boxes, and other locations indoors where they can find food and grease at night.
Apparently, the appearance of six or more of the huge worker ants means a nest has been established and since we were seeing hundreds, we figured we were dealing with an entire colony with multiple queens laying eggs.
Unfortunately spraying insecticide and killing the foraging worker ants does not get rid of the colony. The only option is to directly spray the nest, assuming you can find it. Even this approach is not successful unless the ants are trapped and cannot scurry away to a new location. Even ant baits are usually ineffective with these type of ants.
We determined that most of the ants were coming from the kitchen near the refrigerator. At certain times of the year, there are winged males and females that swarm and mate. Worker ants take care of the eggs during the 20 days they take to hatch. As the colonies develop, various sizes of workers are produced. The small ants stay in the nest and the biggest ants protect the nest and look for food. We found a pile of elongated, whitish eggs next to the refrigerator in a small crack in the floor. We were able to vacuum the eggs up and spray the area.
Since then the number of ants we had to squish has gone down every day and now they have disappeared. We wonder what tropical bug we will “learn about” next.