What kind of plants?

There are scale, aphids, mealybugs, caterpillars that could fit the description.

Do you have ground space for gardening? Many plants that hummingbirds would visit are hardy in Z6, not necessary to save inside over winter.

As purpleinopp said, it could be different things, but I'd bet you a fancy dinner that it's a mealybug (which is a scale) infestation.

You can try insecticidal soap, which might work, but sometimes doesn't. Insecticidal soap, probably will set them back, but may not completely eliminate them. Also, you very well may have to spray a few consecutive times for the soap to be effective.

I've used Bayer Advanced Tree and Shrub Insect Control (which is systemic) on houseplants, for this problem, and it has worked very well. Technically, you should take the plants outside before treating them and leave them out for at least a few hours. I personally have never bothered doing that, because I consider (after researching it a bit) the dangers of treating with this chemical, indoors, very low. I am not saying that others should necessarily do this.

Dicliptera suberecta (Hummingbird Plant), which is likely what Ponyexpress is talking about, is not hardy in zone 6a. An unheated garage might work though.

Thanks for your replies. I had cuttings of Salvias, cupheas, and lantanas. A few others too. I looked up mealy bugs and this is what they looked like. Thank you.

Glad to try to help point you in the right direction. No idea on the Salvia or Cuphea, but Lantana may be able to be stored dormant if you have a basement or crawl space. You're so close to where they are hardy, and they do go dormant even down here most winters, growing back from the roots in the spring. Maybe someone who's done that kind of thing will pop by with specific advice about keeping a Lantana this way.

With plants temporarily inside for winter, I don't get too wigged out if I see a bug. I'm inspecting often enough to notice then right away, when most can be rinsed off, dabbed with a cotton ball/q-tip moist with rubbing alcohol, or sometimes go away if the plant is left to dry out, diff strokes for diff plants/pests.

You mentioned seeing 1 critter. Simply removing it should solve the problem, be on the lookout for more though, plant pests don't usually lead solitary lives. Sounds like you might have caught the situation right away, that's good.

Although perfectly healthy plants can get pests on them, keeping plants as healthy as possible is the first step to avoiding bugs. Things like providing enough light, not rotting roots with soggy conditions and/or water sitting in drip saucers, keeping the soil surface and plant clean of dead debris are proactive things you can do while inspecting often.

Be careful about using rubbing alcohol; it can burn many plants. I've seen various people (don't remember which) on here recommend using 1 part alcohol to 3 parts water. I tried that once and got slight burning (didn't really hurt anything in the long run). I don't know if the mixed alcohol would be any less effective or not. If you do decide to use alcohol (either mixed or unmixed) you may want to do spot tests on your plants first.