Home

Photo gallery for Carpenter Ants in Insulation, with Remediation

| Image 1 of 5 |

Scene of the Crime

Scene of the Crime
Ingress Hole
Run ant, run
Pic5
Pic4

Carpenter Ants in Insulation, with Remediation

Mon, 03/15/2010 - 19:51 — schillingjs7
Author: 
Jonathan Schilling

Carpenter ants (Camponotus spp.) were discovered in the walls of a suburban Minneapolis home. Ants were identified using the following characters: 1) individuals had a single node between thorax and abdomen, along with a narrow junction between abdomen and thorax, unlike termites, 2) there was an angular front top end to the abdomen (see picture), 3) there was a circle of hairs around the anus at the tip of the abdomen, 4) all individuals were black (unlike termites which have creamy white individuals, and 5) it was infesting this house in MN, clearly a pest but would have really been at the geographic range limit for a termite. This is likely Camponotus pennsylvanicus, being in mid-USA.

Once discovered, the damage was located as being in the insulation, although this was verified from the inside and no pictures are available from inside. Ants entered through an anchored portion of the window crank and could be followed in and out. In the cover of dark, the ants were followed streaming out of this nest, a secondary nest. Carpenter ants were foraging for sugar sources (they do not injest wood as a food source - this is why they can colonize insulation). We hoped to track them back to the primary nest, which can be done by following the ants after dusk. We did not succeed, however, so we could not treat the primary nest (likely in a rotting tree or tree with a rotten branch point).

Avoidance Strategy: 

This could have been avoided by keeping moisture content lower in this area of this house. This was an add-on, built over concrete with styrofoam insulation added. Insulation was inadequately thin. There was visible rot in the window sills, suggesting the room suffered from temperature fluctuations that could have been avoided with better vapor barrier and temperature control. Condensation on the exterior barrier in winter and on the inside wall in summer is a common issue in cold climate buildings if moisture is improperly managed.

Remediation Strategy: 

This problem was successfully remediated using insecticide baits, but only in the nest in the house. Without dealing with the primary nest, this issue remains in progress. There are many baits available to users at the hardware store, etc. This was provided by an ant specialist to me, as a first round attack. We used a squeeze gel bait and it worked within one week. After 3 weeks, the house was reinspected with no sign of the ants. However, the problem was caused by avoidable issue in the building, and this has not been fixed. Many further problems could arise, and it is important that the building issues with moisture be dealt with. That said, if carpenter ants are an issue again, another consideration is the availability of vegetation and honeydew sources from needles and other leaf types, upon which these ants subsist. Building a secondary satelite nest in the house was not a coincidence. There is heat. There is also likely food nearby.