Spider mites are a type of spider that can wreak havoc on your bonsai if you are not careful.  These pest survive by sucking at the cells of their pray.  They are very common when growing Juniper bonsai trees outdoors.  These mites are also common pests to turf grass in many locations.  Be sure to check newly purchased trees for pests before placing the tree near other bonsai.  This is the most common way that these pests are spread.

These pests reproduce at a rapid rate with many overlapping generations in a single season. An egg can hatch and become a productive member of the family in less than a week under good conditions.  From there, a female can lay several dozen eggs in its lifespan.  If not treated, the minute spiders are able to take over the plant and easily killing it within weeks.

Signs of Spider Mites

You will notice while spots on the trees foliage from where the mites sucked out the cell contents.  These spots will start to turn yellow or bronze over time.  When highly effected, you will notice webbing within the foliage.  They use this webbing to protect themselves and their eggs from natural predators.

How to remove Spider Mites

Spider Mites are one of the most common pests for bonsai growers because regular insecticide does not kill them.  Instead, insecticide kills their natural predators and leaves them with an open breeding ground.  Kill spider Mites with mitocide, as nothing else will effectively remove them.  For immediate results, spray the tree foliage with a high pressure hose.  This will remove the protective webbing that keeps the predators out.  This will also remove many of the mites and eggs, damaging the life cycle.  If you continue to experience breakouts, you can purchase predatory mites online.  These mites will stick around without damaging your trees, eating only the spider mites and other pests.