Eric G wrote:

I have a mealybug problem with my houseplants and wonder if someone
can offer some suggestions on how to get rid of the pests?

These are the white mealybugs.
I had to throw out 5 or 6 large Diefenbachia plants because they were
so infested that it was hopeless.

I have a few other plants infected with the mealybug but it isn't out
of control yet and don't want to lose the plants.

You are pretty much going to have to go in hard with systemic chemicals
if you want them all gone. And move all the infested plants well away
from the clean ones. You could start with a knock down contact
insecticide to kill the obvious ones and then use an aggresive systemic.
One of the Phostrogen plant pin type was found to work well for cacti
and most succulents YMMV.

Using hydrogen peroxide with cotton swabs just isn't practical. It
takes forever just to do one plant.

Meths and a stiff brush is faster.

I bought an insecticidal soap and have been using the spray once a
week on the plants, but the mealybugs still keep coming back.

Not a chance. You just get cleaner mealy bugs.

I read about using biological control (beneficial insects) and would
like to explore this avenue if possible. Is it practical for indoor
plants? How do you go about the process?

Throw the plants out if you are not prepared for chemical warfare.

And don't use anything too nasty on indoor houseplants. A few unlucky
cactus enthusiasts have been seriously injured using dangerous
commercial greenhouse insecticides in the home.

Regards,
Martin Brown