Dendrobium orchid from Thailand looses leaves FAST

[ro0ter]

Thank you very much, Philip. At least I know my enemy now. I need to grab some good weapons against these swarms.

The isopropyl alcohol did quite some good job, but i still see some solitary mites on the stems and leaves and also in the crowns... That concerns me most... The ("still" I should say) "healthy" orchid has now 2 base keikis, but their crowns seem to have those ugly red dots...

About the insecticides I have, here they are:
1) some room spray against all sorts of bugs, ants, mosquitos, moths and spiders (general purpose like, brand AROXOL) which contains D-TRANS-TETRAMETHRIN and CYPHENOTHRIN (both 0.15%). when I sprayed it on the orchids, I noticed some root burns (dark, woody) - maybe the (iso)butane/propane frost bit them (saw it bubbeling on all the surfaces, maybe i was too close)
2) some general purpose insecticide (brand AMIA) against moths, aphids and (lol, here it comes, driple coincidence) vinegar fly... I have bought this one as I thought it will help me get rid of the "fungus gnats" which I took as mealy bugs... The active ingredients are PIRENONE and PIPERONILE BUTOXIDE. I noticed no adverse effects on all my orchids.

Yet, I will search for insecticide containing what you suggested and read further on this forum about these freaky "pets"...

Have a great day!