mobenchain, you have a formidable problem but it can be solved. Think Eliminate, Reduce, Protect and finally, Control; not as isolated items but as an integrated plan. By removing some host plants you have already done some of the first two. Consider ways of doing the same on the remaining plants, like pruning the most affected parts. Note that the primary purpose of this pruning is for pest control and it may clash with the aesthetics. You will have to make that choice. Take the plants outside and hose off (protect the soil against the heavy watering). A hose-end shutoff, opened just enough to give a thin, forceful jet will knock mealy bugs out of leaf axils without dislodging too many leaves. If the plant is too tender for this treatment, use a sponge to do the job. You will be using water volume, rather than pressure to get rid of the pest. I cannot think of practisable protection devices in your situation but think of how you can use sticky traps, netting covers and barriers to prevent reinfestation. Control methods offer the best hope. These can be mechanical like glue traps and sticky (on the OUTSIDE only) bands on the stems near ground level. Cultural controls embrace watering and can include manipulation of the environment. Can you lower the temperature in this space long enough to simulate winter? Painting the room has possibilities. A newly painted room, locked up for a week or so may make the air toxic to small insects-I do not know. Biological methods will include elimination of ants, introduction of lady bugs, (I do not know how this will work with that painting operation) and others which I cannot recall right now. If your philosophy includes the use of chemicals, I would recommend a pyrethrin (not pyrethroid) formulation. The latter are tweaked to add properties like residual- the same property for which other chemicals were withdrawn. Scales pose special challenges. Even when they are dead they persist and look terrible. An oil spray (I recommend, not endorse, "Volck") will smother the crawler stage but once they are established on the plant, only a systemic or hand picking will control them. 'Going forward' as they say, inspect your plants on a weekly basis and try to catch the FIRST insect. You may not succeed in doing that but you will not have a serious outbreak. I would not worry too much about these insects infesting other places like walls and glass surfaces. Routine housekeeping practices will take care of that; but do keep a sharp look out for honeydew on surfaces like plant containers and tabletops. You have a most interesting challenge and in the end you will be able to teach us all a few things.

Yes, I mean red spider mites. Looks like I've a bit forgotten my english vocabulary! Actually, the infestation was quite small, nothing that would harm the papaya. The strange thing is the papaya started withering right after we removed the mealybugs, and I don't see how mealybugs could balance the effects of red spider mites. Concerning the 'very special indoor conditions', the fact is many people bought papayas at the same place, they have mealybugs too and we don't know how to deal with them. We all live in 9m² student rooms and all the papayas are fine, except for that mealybug problem. Anyway, thanks for your answer, Rhizo !

Thanks Kara for the quick answer. Yes it's the bright white fuzz! They were making me crazy but now they're almost gone (I think). They are in a cactus mix I bought online. It says on the website it has standard potting soil, washed sand, coconut shell powder, worm castings, crushed pine bark, perlite and crushed vegetable charcoal. I have two other cactus and some succulents in the same mix that are doing great, no bugs or anything. I keep them far from the infected ones. Is it ok to repot again since I did it just 3 to 4 weeks ago? Ew, scales. I'll prepare for surgery. There are some small orange spots between the big black ones, could them be scales too? Just in case, I took more photos and zoomed in on the light brown spots of the cactus of the 3rd photo: Are they scars or scales or both? Thanks!

Brian, you might not have any bugs because you do a great job at growing them and they are too healthy to even consider attacking. And too, you nay not be picking any up because you keep them inside all the time. Too you may not be getting any from inested plants once bought. I have not seen you say you got rid of them or had a bad pest problem and got rid of them with this method. Just a thought) Tropico touched on a lot of things I was thinking. Many of us use the methods Tropico speaks of and in fact I have to before I bring mines in. If I don't hit them with Fish Emulsion weeks before bringing mine in, they will get pests. In fact, I constantly wipe down my Phals with half strentgh Alchohol and half water, then I add Dawn dish soap, the 'blue ' one which does not harm any of my orchids. In fact it shines them up and prevents dust and spider mites. Horticultural Oils have never harmed a tree of mine or a plant, as long as it's applies as directed.) Mike