Wood destroying insect damage or something else?

Came across structural damage to exposed framing in the basement ceiling, specifically a rim joist and joist. When I poked the rim joist, it just crumbled and large chunks were easy to pull out. Lots of wood dust. Contractor tried to sister a joist, but did an inadequate job of it. I’m going to write hard on this and recommend repair. I know I don’t have to tell my client what caused it, just that it needs fixing, but I still wanted your opinions on what did it. 1897 row house, New Jersey, wood was dry as a bone, I didn’t see any mud tubes, a kitchen sink was above it (no other plumbing). I was thinking it might have been wet once upon a time and carpenter ants got to it (or termites and the tubes were cleaned away with the rehab). Is there any possibility this is some kind of rot or damage not from an insect but another organism? Thanks fellas.

That’s some old stuff you have there.
Pic #2 looks like old wood decay and past anobiid beetle damage.
It can take years for a full life cycle.
Good luck! :cowboy_hat_face:
MG> State Lic Termite/Lawn & Ornamental/Pest Control Rodent Operator

That’s for sure, must have been leaking since the day it was built.

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Thanks Marc. Powderpost beetle crossed my mind but I didn’t see all the little holes that usually accompany it. As you said, it’s some old stuff and and it was in such bad shape in that area I shouldn’t have ruled it out.

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Looks like dry rot from being wet in the past. Something that old may have had some termite damage as well, but mostly dry rot.

It may have WDI damage too, but what I see is just a lot of advanced wood decay. Common in old log and timber homes here in Colorado. Those timbers have lost a significant percentage of their original strength. Fasteners into that stuff means almost nothing.