Okay, no swimming with sharks. (But, hey, whatever you and the tarantula have going on, well, that's not really any of my business. ;) More seriously, I've got good news and bad news (but both are kind of gross news). The good news is that the worst is probably over. The bugs that came to visit your late neighbor probably laid eggs and then died off shortly after your neighbor left the building for the last time. The eggs probably took a couple weeks to start hatching, and that's why you're seeing them now. Pretty soon, they're going to figure out that they're not going to get the same deal their predecessors did, and head off to greener pastures. The bad news is that if you do have anything at all for them to eat, some of them will stick around. And in order to figure out what they eat, you'll have to figure out what they are. A google image search will probably do the trick, but not without your having to look at a lot of pictures of a lot of bugs. In the meantime, you might try diatomaceous earth. It kills just about every bug I've ever heard of, and it's remarkably safe for humans. You should avoid breathing it in any quantity, but you could eat it without ill effects. In fact, the best place to get it is from pet shops or feed store that sell it for deworming animals. (There's a cheaper, lower-grade form that is sold as a swimming pool supply, but that's not the kind you want.) It's a fine powder made up of little microscopic fossilized shellfish: the sharp edges of the shells are to fine to bother humans & non-insect-sized animals, but are just the right size to do the insects in. Good luck! Let me know how it goes.

There is plenty of orchid bark on hand, for humidity will have to check tomorrow. Too much right now I am guessing. Looks like we have a tiny orchid society after all, will contact them after I speak with the department. The pots are more holes than solid really. And definitely getting a better watering regimen. Will have to see if I can find colored plant tags, will be useful to color code in there for future students. Thanks for the help to, very appreciated. Will probably have more questions as I move forward, about separating, repotting, and pruning roots of they are as rotted as I fear. Hopefully the orchid society can lend us a hand too. Good practice for me, sooner or later I am going to try growing an orchid or 20 at home. May as well jump at a chance to be useful and boost my ever growing horticulture skills. And knowing I can reach out to you guys makes it a whole lot less daunting.

Hi lizgleeson. I had hoped someone with high expertise in this sort of thing might have responded by now. In that person's absence, here are my thoughts but keep in mind I'm a long way from being an expert in Eucalyptus dieback. The natural range of Angophora costata is a long way from south western Queensland where you live so your trees are being subjected to quite different conditions from what they would normally experience. It's quite possible that your trees aren't coping with these unnatural conditions (different soil, temperatures, climate, rainfall) & this is stressing them no end. In fact, the photos you provided remind me of Tuart Gums Eucalyptus gomphocephala planted in SA where I live. After a few years they become quite stressed & open to borer attack to which they readily succumb. Have you noticed any grubs in holes in the trunk or branches? From my limited reading on Eucalyptus dieback fungi seem to be a major cause of cankers in Eucalypts. Have your trees been subjected to consistent humidity? (Unlikely in south western Queensland, I guess). Have you been spray irrigating them? (Again, unlikely in s.w. Queensland but might depend on water availability). Another cause of dieback is reported to be defoliation of the canopy, presumably by bugs or larvae. How this works I don't know but the canopy in the last photo looks severely ragged (no offence!). Have you noticed small leaf-eating critters in the trees' canopies? If so, the most effective remedy is to encourage their predators (often native birds) by planting &/or encouraging the regeneration of local tree & shrub species near your Angophoras. However, this will take some time & it may be too late for your trees. Your trees could be severely cut back & may, repeat, may become reinvigorated & shoot afresh. You could try chopping them off near the base to see if they send up new shoots. My preference is to plant trees which are local to where you live. They've survived for many thousands of years where you live & are adapted to your local soil & climate so if your Angophora costata don't survive you could replace them with local species. You'll find that local species are more likely to attract local birdlife so this could be a bonus for you. If my thoughts are way off beam then let me know but I must admit my curiosity about your problem is high. Hopefully, we'll hear from an expert soon.

It's likely powdery mildew, in that case. http://livegpath.cals.cornell.edu/gallery/tomato/powdery-mildew-on-tomatoes/ http://utahpests.usu.edu/IPM/htm/vegetables/vegetable-insect-disease/pm-tomatoes/ I personally would try neem oil or potassium bicarbonate. Sulfur is considered highly effective on powdery mildew, but in hot weather, it's easy to burn plants if you use sulfur. There are many non-organic options as well.