Why are roaches coming up through my drains?

What people tried

Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.

1. 1
   Running water periodically to refill dry P-traps
2. 2
   Putting baby or mineral oil in the drain to prevent trap evaporation
3. 3
   Duct-taping the overflow cover shut
4. 4
   Dusting plumbing access areas with insecticides like Nibor-D
5. 5
   Using roach gel bait or aerosol sprays
6. 6
   Hiring a plumber to run a camera or perform a smoke test for broken pipes
7. 7
   Killing the spider upon discovery
8. 8
   pull the dishwasher out of the cabinet and then seal the holes that exist at the back of the cabinet
9. 9
   Call an exterminator and/or talk to your landlord
10. 10
    shoot a full can of expanding foam insulation in there

In their words

Unedited, most upvoted first, each linked to the thread it came from.