Mealy bugs are one nasty insect. You should really familiarize yourself with these destructive, hard to control insects. Catching them early may be your only chance at control.
Finding Mealy bugs any time of the year is unwelcome. If you have a greenhouse, you can depend on them showing up when the plastic goes on and the plants go in.
If you find mealy bugs on your plants in late summer/early fall, get to work-you MUST control them before bringing them inside or putting them in a greenhouse for the winter.
These insects with sucking mouthparts can do a lot of damage and get out of control in a short period of time. They also have a long, long list of plants that they will go for. Most insects are pretty host-specific, but not these! They lay their eggs in the axils of the leaves where it is difficult to get a pesticide to, and they secrete waxy threads to cover themselves, their young and their eggs, protecting them from annihilation.
By now you can tell my relationship with these insects is not good. In fact, if I find them on one of my plants I am more likely to bag it and put it in the trash than I am to try to rehab it.
From the recent reports this October, you should be checking your Lantana right now, and if you find Mealy bugs, check every other plant in the vicinity. They like them all! Hibiscus, Texas Sage, Yaupon Holly, and on and on………
The first thing I would do is cut the infected plant back as much a s possible to limit the number of Mealy bugs you have to kill. Bag the clippings and tie the bag tight! If temperatures are between 45° and 85°F and the humidity is below 50%, spray plants thoroughly with Bonide All Seasons Oil Spray. In fast-drying conditions it will suffocate the little buggers. You can follow up in a week or so with any insecticide listed for mealy bugs on the label.
Bonide Rose Shield has also worked pretty well for me. Be sure to read the label and follow the instructions exactly. Re-check the plants often. Like I said, they area a tough one to get rid of!