Do Pharaoh ants eat sealant?

Question

My high-rise apartment has had pharaoh ants for the past 3 years (maybe more). It is being handled by a pest control company. I am not looking for countermeasures.

One of the countermeasures advised by the pest control technician is to seal the opening through which my water pipes travel. The apartment management sprayed a sealant that looks like whipped cream, but had a distinct chemical smell (images below).

The ant sightings are usually on the kitchen counter top, mostly around the perimeter of the sink. I try to wipe the counter often, and keep the area dry. The sightings were getting kind of low just before the hole was sealed, sometimes going for days without a sighting. Since that day, however, the sightings have been on the upswing. Quite a coincidence.

I wondered whether the pharaoh ants are attracted to the chemical sealant as a source of food. Googling doesn't turn anything up for pharaoh-ant-eat-sealant. Does anyone know about the plausibility of this?

Answer 1

The sealant in question is a self-curing expanding urethane foam, marketed under numerous brands and formulations in the US and Canada such as DuPont Great Stuff, Loctite Tite Foam, and DAP Touch 'n Foam. It is widely available at hardware stores and home centers.

After curing it forms a hard cross-linked polyurethane mass - essentially a plastic foam. While it has no nutritional value and is solid enough to be marketed in a pest control application, it could theoretically be chewed through by a determined-enough ant colony, as the marketing material for that particular product doesn't say anything about insect repellant properties, only mice. Non-rodent-repellant formulations are known to be susceptible to eventual "chew-through" and inhabitation by both mice/rats and insects such as carpenter ants. Great Stuff markets a Pest Block formulation that supposedly is formulated to prevent chewing, but its claims regarding insects are a little vague. You'd have to ask your building management if they used a pest-blocking foam.

You say that the sightings started to swing up again a day after the sealant was applied. I would imagine that it would take some weeks for a colony to chew through the amount of foam pictured (even longer if an insect-repelling product was used), and they would need a rather compelling reason to keep at it, as the foam itself is not a food for them. It's likely that you're seeing ants that were already in your apartment when the "escape routes" were sealed, and they're simply foraging in a more visible manner now because they don't have other sources of food. On the other hand, the fact that you think you're seeing more ants now after the pipe openings were sealed could simply be a coincidence. Remember, correlation does not mean causation.