Q&A: Insect Infestation

An insect infestation can be the bane of a terrarium ecosystem.  While an errant earthworm, ant or snail may not do severe damage an entire host of winged insects can spoil your tiny garden.  Here's another Q & A about this common problem.

Question: I recently made a moss terrarium with live moss bought from Idaho. After a week or two after I placed everything in my glass jar, I noticed very small white mite looking insects crawling on the glass. I researched for hours and couldn't find anything pictures of the insects. They don't jump or fly, and seemed to be in the hundreds crawling on the glass. I tried putting a cottonball soaked in pesticide in the closed terrarium for a week plus. I didn't see the bugs again. I bleached the terrarium, put new substrate in and within 2 weeks the white tiny mite looking bugs were back. I threw everything out in fear the bugs were crawling in my house and not being able to identify them was scary to say the least. I just went back to my homestate of Illinois and went moss hunting so I can try once again. I'm going to go through all your steps and quarantine the pieces to see if anything happens. Have you had this problem before? Do you have any advice on how to treat them if I do have another problem? Thanks so much!

Answer: I believe that washing your moss and observing it under quarantine should prevent the insect infestation from taking place again.  I would recommend observing the moss for two weeks in quarantine just in case the insects are taking that long to hatch or mature.  Two weeks is a long time to quarantine moss so make sure to not over/under water or let it suffocate in a poorly ventilated container.

If the insects are not native to your moss - I can imagine two other potential problems:

• Your soil may be contaminated if you are not using fresh, bagged potting soil.  There are methods to "sterilize" soil by baking it on a cookie sheet in an oven at low temps.  It may be something to consider trying and here are some further instructions at Tipnut.  

• If you fear that the insects may enter your terrarium from elsewhere in your house (another houseplant perhaps)?  You may want to lid your terrarium for 80% of the time or consider rubber banding a piece of gauze or cheesecloth over the opening of your terrarium to prevent insect colonization.