Do pests cause long-term electrical issues?

The honest answer to this question depends entirely on what "long-term" is doing in the sentence. If it means "can pest-caused electrical damage sit undiscovered and cause problems for a long time," the answer is yes — a gnawed wire from months or years ago can produce an intermittent fault that comes and goes unpredictably, which is exactly the kind of symptom that's hard to trace and easy to live with until it isn't. If "long-term" means "does the damage keep getting worse on its own the longer it's ignored," the answer is no. There's no physical process by which an exposed conductor continues to deteriorate once the animal that exposed it is gone.

A wire that's been gnawed down to bare or thinned conductor doesn't necessarily fail outright — it can sit for a long time only intermittently making unwanted contact, triggered by vibration, a temperature swing, or a loose connection at exactly the gnawed point. That's why symptoms like a breaker that trips "for no reason," flickering lights, or an outlet that periodically stops working can persist for a surprisingly long stretch before anyone connects them to old rodent activity. NFPA's research on home electrical-failure fires names arcing as the leading contributing factor, and a previously damaged conductor sitting in that intermittent state is a plausible, if hard-to-quantify, contributor to that category.

Cockroaches don't gnaw wire, but German cockroaches sheltering inside warm electronic or electrical equipment can leave droppings, shed skins, and body residue that bridge or corrode a contact over time. The result can look similar from a homeowner's perspective — an appliance or circuit that misbehaves intermittently — but the underlying mechanism is fouling and corrosion rather than insulation loss, and it's generally a slower, less hazardous process than an exposed live conductor.

It's worth being direct about the part of this question that's overstated: nothing in the evidence supports pest-related electrical damage compounding on its own after the pest is gone. The damage is a fixed physical defect at a fixed location. What changes with time is simply the cumulative odds of that defect triggering a visible symptom — not the severity of the defect itself. That distinction matters because it means the fix is straightforward and finite: find the damaged section, repair it, and the "long-term issue" is over, rather than an open-ended problem that keeps needing attention.