Question
i have 3 large plants, each are about 3 years old.   they had mites in the early summer and lost all their buds, i used a systemic fertilizer and insecticide and they grew well all summer, but no new buds. now i have brought them into the house for the winter, and they all have what i think are spider mites. they are droping leaves, have webs in their axles, and long thin webs that drop from their leaves...what can i do? are my other plants in the sun space at risk?

Answer
Spidermites -- Tetranychus urticae -- are the perfect illustration of that S. A. T.  word, UBIQUITOUS.

Because every Winter, they're everywhere, on everything.

It's not a matter of IF your other plants get Spidermites.  It's a matter of WHEN.

I have to say right off the bat: SHAME ON YOU SUZANNE for your profligate use of Systemic Insecticide.

SO outdated, Suzanne.  So anti-Environment.

If you had simply deployed a single dose of your local Ladybugs, these friendly little red and black Beetles would have gone on a RUTHLESS Search-And-Destroy mission against EVERY LAST SPIDERMITE, devouring them ALL.  Mission Accomplished.  

I'm not kidding.  All you have to do is sprinkle Ladybugs around the base of a plant and eat all the Aphids and Spidermites out there.

Systemics wipe out everything and everybody.  Doesn抰 the Skull and Bones worry you?   When you use these against Spidermites you lose all natural anti-Spidermite organisms as well.  Systemics are not selective.  They just kill, kill, kill.   So getting rid of them in the Summer, outdoors, is a piece of cake.  Until someone comes along with insecticides, Soil in the typical U.S. Garden is PACKED with Predators and Fungi that are HOSTILE TO SPIDERMITES.

Controlling indoor infestations of Spidermites is unfortunately much trickier.  And their damage speeds up when the cold weather heat is turned on and temperatures rise indoor.  Not only do the Mites get hungrier, but dry air accelerates the evaporation of their excreta.  Plus heat alters leaf chemistry that makes plants more nutritious for Mites.

The Colorado Coop Extension website explains everything:  'High temperatures (up to 100 degrees F) decrease the life cycle [of the Spidermites] from three weeks to a mere 5 days and low humidity allows the Mites to more easily remove waste products from their bodies via evaporation, thus enhancing feeding and reproduction.?br>
See that?  FIVE DAYS!  You can read it online:

http://www colostate.edu/Depts/CoopExt/4DMG/Pests/spidmite. htm

That抯 why HOT and DRY are the Spidermite抯 FRIEND.  HUMIDITY and COOL TEMPS are the Spidermite抯 ENEMY.

I would like to know just as a point of information what 'systemic fertilizer and insecticide' you used.  (As you can see, they are not so permanent -- on the plant, at least).

Spidermites start building families when temperatures hit 80 degrees  F.  It takes 5 days for a Mite Egg to hatch and grow up.  FIVE DAYS!  And  they live for a month!

EACH hatched Mite begins laying 300 eggs! Poof!  

Watering is a critical component of the battle against these Mites.  And if  you're thinking of treating your houseplants to another chemical snack to help them recover, forget it.  Fertilizing just sweetens the  deal for the Spidermites -- especially with Nitrogen Fertilizers -- by  generating more of the delicious Amino Acids that make up Green plant  cells.

Boosting Humidity is an important measure to take to address the current Mites bloom.  Wash leaves and branches, and spray or Humidify the room to keep the Humidity up.  That much H2O keeps leaves moist.  Rinse them 2x or 3x a day.  Wash the undersides gently.   You will wash all the Spidermites and their children and eggs away.  

Your biological control options for next Summer are highly encouraging.  Researchers at University of Maryland posted a report, 態iological Control  Options for Spidermites in the Greenhouse? where they studied strains of  the Spidermite Fungus 態eauveria bassiana?  The JW-1 Strain,  which is currently sold to the greenhouse market as a product called  慛aturalis-0?by Troy BioSciences, was most successful: In their report, researchers pointed out, 慣he mode of action of the Fungus begins with the attachment of  Fungal spores, or conidia, to the insect cuticle.  The spores germinate and  produce infection structures which penetrate the pest's cuticle.  The  Fungus then grows into the body of the pest.  If the Fungus can overcome  the pest's natural immune system, it proliferates in the body and kills  the host.  It is key that sufficient numbers of viable spores contact  the pest for infection to occur, so excellent spray coverage is  essential.  The pest picks up the Fungus at spraying time or when it moves over  the treated leaf surface. ? Better living through Biochemistry and Microbiology.?br>
Meantime, those Colorado folks list some little known Spidermites side effects you may be aware of:  They say that Spidermites 慳re a known source of allergens causing Asthma, Hay Fever, and Contact Urticaria.'

How抯 your breathing, Suzanne? Any strange skin rashes? Sneezing a little more than usual?

Summing up (must be dinnertime by now), let抯 try not to use ANYTHING on your plants with a Skull and Bones on it or any WARNINGS, period.  You抣l live longer, trust me.  And the Spidermites will live shorter.

Indoors, during Winter, Water Water Everywhere will raise humidity to levels that give Spidermites a terminal headache.  Come Spring, plan to conduct biological warfare against them.  

And do not fertilize with any Nitrogen until the Spidermites are under control.

Any questions?