We’re quickly approaching spring time and you may even be experiencing some warm days as winter dwindles. At this time of year we begin to see certain insects awaken and appear in the home. Two species you may encounter first are the odorous house ant and the citronella ant. Both of these species will nest near and under homes, using concrete slabs, logs, rocks, and other spots to hide their homes. They will come indoors to forage for food and water.
Odorous house ants
- Smaller ants, between 1/16th-1/8th of an inch, and are dark brown or black.
- Odorous house ants smell like old coconuts or blue cheese when squished.
- Definitive ID requires microscope or hand lens; look between thorax and abdomen for a hidden node (the bump or thorn looking structure) underneath the front of the abdomen (Figure 1).
- Also known as large yellow ants, the workers are 1/4th of an inch in length and are a yellow-orange color
- When crushed these ants give off a citrus smell, often compared to a citronella candle
- With your hand lens or microscope you can see that their thorax will be uneven, it has two humps, and there will be one node between the thorax and abdomen (Figure 2).
Odorous house ants can be controlled with ant baits. This species has an extremely powerful sweet tooth and will readily visit baits that are sugar based (one example would be Terro Ant Baits). Baits work by having the workers take the material back to the nest to eliminate the whole colony over the course of 7-10 days. You should clean up any food sources to force them to feed only on the baits and avoid spraying individual workers with liquid or aerosol products. If you treat these foragers they won’t be able to take the bait back to the colony.
Citronella ants may not take baits as readily as their smelly cousins. You may find success with sweet baits but you will likely have to find and treat the colony directly. This is best accomplished by hiring a professional but you can try following the ants back to their home and treating the site directly. If the nest is in soil you can treat the soil directly with a product labelled for use in the yard.