We have suddenly (for 1 month) been seeing some springtails coming out of our bathtub drain.Our house is 55 years old w/ the original tub and drains and traps. We also are noticing a slight foul odor from that same drain. We have quarterly pest control, and have been doing so for a few years now. They say that they can't do anything for the springtails because springtails only appear from moisture. The house is on a slab, and the pipes are under the slab. Is this a pest control or plumbing problem? There is no water backup--how do we get rid of these sudden pests in the bathroom?Thanks for any help or suggestions. A plumber came out and sees no signs of leaks,etc.