Dear All, Fortunately I do not have mealy bugs in my collection except the odd new plant that brings them with itself, in these cases I use Imidacloprid (not always effective) or dimethoat (very effective) If the plant is not valuable I would throw it away. But I think if a whole greenhouse is infested with mealy bugs spraying is of no use: In this case I highly recommend biological pest control which works very well for me with spider mite and scale insects. The approach is different: predating insects would be killed by pesticides or the remains or breakdown products of them. Companies supplying predators have lists for how long you need to wait after chemical treatment according to the chemical and the predator. When biological control is used it is important to start it at the very fist sign of infestation. The predators need time to multiply, to find the pest and most of them also need a certain minimum temperature to act and/or survive. The best results I had with spider mite, with one or two releases of predating mites I am clear of that horrible pest, nothing else worked before I discovered this method. And it works better the longer I use it, it feels as if there is a certain permanent population of predators present now. Less sucessful was a predator against whitefly, it took very long to eradicate it and now they are almost gone but I still see the odd white bit flying or sitting somewhere. But chemical treatment nowadays has become virtually impossible. On the other hand some pests cannot be delt with with biological control, for example root mealy bugs. The company I get my predators from has an excellent service. I can send them an infested leaf, they would identify the pest and recommend a specific predator (in some rare cases no predator was known) It gives me a much better feeling to use this totally harmless method rather than using more and more poison as I did in the past, also because I grow edible plants in my greenhouse like grape, fig and citrus. One word about Imidacloprid. It is a good insecticide and so far I have never had any plant damage using it. BUT: it is VERY long acting. This seems to be an advantage at first glance but in reality this is its biggest risk and disadvantage. Because long acting agents take a long time to disappear from plant tissue the active level in the plant tissue will decline very slowly. During this slow and prolongued decline resistance develops because pests can get used to low levels of the agent that just does not kill them. The same applies to long acting antibiotics in medicine by the way. This problem of Imidacloprid was known from the beginning on and it was always recommended not to use it as the only product but use it intermittently with other, non related substances. A good alternative in between Imidacloprid sprayings is neem oil or pyrethrum or a mixture of both. Neem and pyrethrum are much less dangerous for biological predators than Imidacloprid and using the bio method now I only use Imidacloprid in very precise exceptions on a small scale. bye for today, Uli