Question
QUESTION: I understand that alcohol is a good treatment, but I see bottles that are 70% 80% and 90% -- what is the correct strength to kill the bugs and not dry out the plant?  I also heard that mixing a drop or two of liquid soap in the mix help -- do you have any opinions about that?

Thank you.

ANSWER: Dianne, rubbing alcohol (70%) will do the trick.  However, that will only allow you to kill the adults.  Mealies lay their eggs in the potting mix, crevices in the plant, and other inaccessible places.  Think of the use of a q-tip or other material soaked in alcohol as the initial treatment. It could be considered a contact insecticide.  Because it doesn't reach these hidden places, other measures may be necessary.  I prefer to use a systemic insecticide after the initial use of alcohol.  The systemic will enter into the tissues of growing parts of the plant and kill the insects from the inside out.  Even with the systemic, you may need subsequent treatments with the alcohol. Remember, with alcohol, rub the leaves but don't pour it into the mix. If the infestation progresses despite your best efforts, you may need to unpot the plant and soak it in an insecticide solution effective against mealies.  Then discard the potting mix and the pot and repot the treated plant in a clean pot and fresh orchid potting mix

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Indoor Garden   QUESTION: Thank you for your prompt response.  What systemic insecticide would you recommend?  When I last checked out insecticides, I couldn't find ANY that said it would kill mealy bugs or was for orchids.  Maybe I can order it online.  

I have about 50 orchid plants in my apartment -- in three separate areas. There are some areas that rarely have mealy bug problems (mostly in 2 out of the 3 areas) but no area is 100% clear.  One area in particular is worse than the others -- and some species seem more susceptible than others.

Answer
There are two products that I have used with success.  The first is called DiSyston and comes in granules which can be sprinkled on top of the potting mix. The second, more recent product, is called "Eight" prodcued by a company called Bonide.  Your local garden center may have one or both of these and should be able to provide additional suggestions/advice.  It goes without saying to follow the label carefully as these are somewhat toxic to humans as well.  The DiSyston is really smelly stuff so you may want to place treated orchids outside in the shade for a week or two until it gets incorporated into the plant tissues.  For some unknown reason, some plants tend to be magnets for mealy and others less so.  An option is to group and segregate the magnet plants from the others.