Yikes! Mealy bugs indeed! That's quite the infestation you've got going there; it will be difficult to get rid of. First thing to do is isolate this plant from the rest right away. It's quite likely that it has spread to other plants, but you can keep them from getting as badly infested as this one. There's a wealth of information on here about dealing with these guys. For a plant as badly infested as the one in the photo, I would remove it from soil and go at it with a treatment solution and a paintbrush in the sink, to get in every crevice. You will need multiple treatments to get rid of all of them. Good luck!

I feel for you! I've been fighting the battle against white fly and aphids which arrived along with the heat wave. It attacked my moonflowers, nasturtiums and basil. Eventually all the nasturtium plants but one have been thrown out. The basil I'd planted looks much like yours and I have more ready to go in but am delaying until this is under control. I don't know what anyone else would suggest but if it helps I'll share but I've done: I used small amount of mild soap and water in spray container and sprayed undersides of leaves too. Next I put out a dish of cider vinegar with a bit of dish soap and mixed it, covered with saran wrap and poke a few holes in top - that way flies get in but can't get out. I put the dish in the middle of the container pot where I'd noticed the flies in the soil. So far got a couple and haven't seen others - doesn't mean they're gone - just haven't seen the critters. This year I couldn't get to a garden centre where they had ladybugs but YES!! By far in my experience, the best natural pest control. If I'd had that remedy I wouldn't have done quite as much tossing out. The one plant I'm really worried about is the rose (I have only one). I planted garlic in with it and in the moonflowers & of course it will take some time to grow but I'm hoping the scent will put off the bugs. A friend gave me some of her chives - also another good companion plant. Hope you can get the upper hand.

So apparently I wasn't paying enough attention to the weather--we had another heat wave and the plants are heavily wilting in the afternoons. It's hard for me to say if the leaf damage is the result of the heat or the small bug--I'm guessing it's the heat. I'm going to keep watching this and see how things develop. I also looked up our County Extension office and might head over there as well.

Appropriate pot size is determined by soil choice, not by current root or soil volume as compared to the volume of the pot one is bumping a plant up to. When using media that support no or very little perched water, there is no limit to how large a pot might be in comparison to existing pot size or root mass - you can pot a plug in a 10 gallon nursery can with no ill effects. When using media with excessive water retention, one must be very vigilant when it comes to increasing pot size to accommodate a root/soil mass that has become congested. For those that don't know, the term 'container capacity' refers to the volume of water retained in a container medium at the moment it has just stopped draining, subsequent to it having been watered to beyond saturation. It tells us how much water a medium holds against the force of gravity. How many holes there are in a pot has no bearing on how much water a medium retains at container capacity. If using identical pots and equal volumes of the same medium in those pots, the only difference being 1 pot has several large holes in the bottom and sides and the other 1 small hole in the bottom, the volume of water retained at container capacity will be the same in both pots at container capacity. A pot with many large holes will drain FASTER than a pot with a single small hole, but there is nothing significant to be gained when using the pot that drains to container capacity in 20 seconds vs the pot that takes 2 minutes. There might be a small difference in the amount of water that evaporates from the medium between waterings in pots that have multiple holes exposed to moving air, but that difference would be relatively inconsequential, based on the description. Al