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Editor’s Note: This article was reprinted with permission from Techletter, a biweekly training letter for professional pest control technicians from Pinto & Associates.

On a carpenter ant call, one of the main things you need to determine is whether the ants are nesting inside or outside. If you’re able to interview the customer, you can gain a lot of useful information that will point you in the right direction. Here’s a list of nine questions you should ask the customer — and why they’re important — if you have the opportunity:

1. Has your home been treated for carpenter ants before? An earlier treatment may have failed, or a nest might have been missed.

Carpenter ant
Ant: David Cappaert, Bugwood.org

2. When did you first notice the ants? If the indoor activity has been going on for some time, the chances are greater that the ants are nesting inside.

3. How many ants do you see? Large numbers of ants foraging inside makes an indoor nest more likely.

4. Do you see the ants indoors year-round? Ants are not active outside during winter months in cooler climates. If ants are found indoors in the winter, it likely means an indoor nest. In cool climates, if carpenter ants are seen only during warm months, it’s more likely that they are foraging in from outside.

5. Where do you see the ants most often? If ants are regularly in a room that does not have food, there’s probably a nest nearby. If the activity is in a bathroom or near another moisture source, the nest is probably very close. If carpenter ants are mainly seen around an outside kitchen door, they’re probably coming in from outside looking for food.

6. Have you had any wet wood, broken pipes or a leaky roof in the last year or two? If so, where? A structure that has had water-damaged wood or moisture problems is much more likely to be infested by carpenter ants than a building that is dry. Even after the moisture problem is resolved, carpenter ants can continue to nest in the softened wood.

7. Have you seen any ants with wings inside? If carpenter ant alates (swarmers) are seen inside, the nest is almost certainly within the structure. It would be rare for swarmers from an outside nest to end up inside. An indoor nest that produces swarmers has probably been there for at least three years.

8. Have you heard any strange noises inside the walls? Carpenter ants in the nest make a rustling sound sort of like crinkling cellophane. If you hear this with your ear next to a wall, you’ve found the nest.

9. Have you noticed any little piles that look like sawdust? If so, where? Carpenter ants keep their nest galleries clean by pushing excavated wood, dead insects and other debris out through a tiny slit. These “dump piles” are usually located just below the nest site. If no dump piles are found, it doesn’t necessarily mean the nest is not inside. The piles could be inside a wall void and not visible to the customer or the PMP.

The authors are well-known industry consultants and owners of Pinto & Associates, publishers of Techletter.