Like an army of parasitic phoenixes rising from the ashes of a smoldering mattress, bedbugs are back. They’ve invaded United Airlines HQ in Chicago, they’re running rampant in Houston, and just this week MTA officials said bedbugs were found on three N-line subway trains. Two infestations were found Sunday, and another one yesterday. All three trains were taken out of service and fumigated. As for where the bugs were hiding on the train, the Daily News hears the cushions in the conductor cabs were a popular place. Surprising, perhaps, but remember, bedbugs don’t discriminate.