Question
QUESTION: I have 8 orchid plants.  I noticed a small flying bug a while ago in one plant and noticed 1 or 2 from time to time.  Today I looked closely and found several bugs in several of the plants - crawling in the moss and flying around when I moved the plant.  I don't know what to do.  I have read about applying isopropyl alcohol directly; or using a spray mixture of fantastik, isopropyl alcohol and water; or a mixture of cooking oil and dishwashing liquid. In both cases, they suggest doing this every 3 days for 2 weeks.  Does that mean spraying the plant - and what about the moss?  Soaking the moss?  I am freaked!  Should I get rid of the orchids?  I don't know if it originally came from the moss or what to think.  I'd appreciate any advice you can offer. Thank you so much.



ANSWER: Gail, it sounds like you have an infestation of fungus gnats.  The good news is that they don't bother the plants. The presence of these insects is symptomatic of a  potting mix that has broken down as they like to lay their eggs in a soil-like potting mix that stays moist.  While this is great for the gnats, it's not good for orchid plants.  Obtain some fir-bark based orchid potting mix and repot your plants. Once you unpot a plant, discard the old potting mix, wash out the pot thoroughly, rinse off the orchid roots and remove any roots that are mushy. You should use a well-drained pot.  The fresh orchid potting mix may be dry, so you may need to soak it for an hour to break down the water repellancy of the fir bark before use. As each plant is repotted, set it in another area, away from the plants that have not yet been repotted.  Once you have repotted all of your orchids, you may put them back in the same growing area.  If they are in vicinity of other house plants that also have fungus gnats, keep your orchids away from those until you have eliminated them from the other plants as well. Orchid plants like to dry out between waterings so, with fresh potting mix, watering once per week should be about right.

---------- FOLLOW-UP ----------

QUESTION: Thank you for identifying the gnats.  In the past when I changed potting mediums from moss to bark, the orchid went into shock and died.  Would you recommend mixing the 2 mediums together?  

Thanks again.

P.S.  I feel horrible...  I threw out one of the orchids!  I don't know what gnats are capable of, but some of the roots looked eaten up so I got rid of the plant.

Answer
I'm not a great fan of moss.  A little long fibered moss mixed in may be okay but, in time, moss tends to compact restricting air flow to the roots and either staying too wet, or, conversely, drying out making it difficult to re-wet. Many people are unaware or the need to soak the bark-based potting mix well before use.  If this is not done, the bark takes moisture from the roots and creates a radically different environment than a moss-based one.  If some of the roots looked eaten, it could be from some other critters that love a moist environment.  These include sow bugs, bush snails, and slugs. It is possible to revive plants that just have a bit of root damage as roots tend to recover fairly easily if there aren't a lot of rotten roots.