Carpenter Ants in Deck Framing


Old 07-08-19, 08:21 AM
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Carpenter Ants in Deck Framing

I have a 2nd story deck built over a shed style back porch. It is supported on 4x4 posts to the ground. It has a 16 foot span with a double 2x12 microlam beam. I have found carpenter ants in the gap between the two microlams. I believe that I have corrected the water problems that attracted the pests. If the water source is eliminated, will these things go away or should I hire and exterminator prior to re-installing fascia and soffits?
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Old 07-08-19, 08:47 AM
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Carpenter ants are attracted to rotted wood which is caused by water issues!
Old 07-08-19, 08:48 AM
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I don't know enough about carpenter ants to say but I wouldn't rely on them leaving on their own. Bare minimum I'd spray them with insecticide.
Old 07-09-19, 02:56 PM
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Carpenter ants will live anywhere in anything. They prefer wood that is or at least was wet as they find a mold or fungus that they like. The previously wet wood was and probably still is desirable enough for them. They won't go away on their own.

They chew into wood to make a hollow/void space to live in. They don't eat the wood like termites do. Because they don't eat, they don't always chew it either. Oftentimes I've found them living in wall/ceiling voids between structural members or in the gaps between boards like it seems you have described. I've peeled back attic/basement insulation and found colonies of hundreds; no chewings or frass noted.

Unlike termites, carpenter ant colonies can get too big to sustain themselves. When that happens, a new queen emerges and recruits a cross section of the colony to go with her. Literally overnight they will move into a desirable place. If you have mature trees around then that is where a "satellite" colony could come from.

An excellent carpenter ant treatment is to get a liquid concentrate containing the Active Ingredient: Fipronil, mix it with water according to the label (about 1oz/gal water) and spray a high and low exterior perimeter. Treat as a band and crack and crevice. Fipronil is non-repellent which is important to its success. Don't use other insecticides as that will defeat the non-repellency strategy. It will kill the colony slowly, probably two weeks more or less. Spray mature tree trunks that are in close proximity, about 4 feet up from ground. Look for ground nesting ants and treat as well.

Examples of brand names would be Termidor; Taurus SC; Fuse and other.
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Old 07-15-19, 07:32 AM
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Thanks PA

That was a very concise response. I've been away for a few days. I did hire a professional to treat the area and for a while I am leaving the beams exposed prior to re-installing fascia and soffit. The pest control guy used Nuvan 5481-13, MAX Force insect granules as a perimeter treatment and bait stations in kitchen and baths. I have tested and believe that I have solved the drainage issues that kept the wood wet. As always, I am very appreciative of the responses I get on this forum.
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