Spiders = Good Spider Mites = BAD
Spider mites
Prevent: Keep your growroom clean. Fully disinfect growroom with pesticide and 5% bleach solution before growing again after infestation.
Identify: A spider mite lives underneath the leaves of your plant and is invisible to the naked or untrained eye. These mites exist by sucking liquid that keeps your plant alive. They have eight legs and are classified a spider rather than an insect. Spider mites will be fully visible under a magnifying glass of 15x or greater. The mites are yellow/white, red, or most commonly are brown with two spots. These mites will spin webs which are a little easier to spot, but unfortunately mean the mites have been around awhile. Misting undersides of leaves will make webs much more visible and aid in detection. Females become fertilized for life once they mate and lay about 100 eggs every 5 days. 75% of all spider mite eggs become female.
This is the end of the progression of leaf damage due to spider mites, shortly after this point the leaf will die off completely. Note the stippling and spotting across the leaf.
Eradicate
Repression: Mites thrive in temperatures of 70-80F/21-27C with average to high humidities. Cooling off your room to 60F/16C and dropping the relative humidity will slow the reproduction and damage rate of the spider mite. 50% humidity and below is where they get uncomfortable. Spraying jets of water across undersides of leaves will literally blast colonies loose and slow the march of these pests considerably.
Predators: Neoseiulus (Amblyseius) californicus and
Mesoseiulus (phytoseiulus) longipes are the two most common and effective predators available for purchase. These predators can eat 20 eggs or 5 adults daily and die when their food supply (i.e. spider mites) has been exhausted. 20 predators per plant is a good jumping off point.
Manual removal: The tiny size of the spider mite makes manual removal ineffective.
Sprays: Neem oil is the most effective. Other effective methods are pyrethrum, horticultural oil, and insecticidal soap. Spraying three times at 5 to 10 day intervals should be sufficient to destroy a mite population if sanitary conditions are maintained. Eggs of the spider mite hatch in 5-10 days. The first spray kills adults, the second will destroy newly hatched mites, and the third will kill the stragglers. If you choose to use pyrethrum, rotate to another chemical if you spray frequently. This will ensure mites will not develop a resistance to synthetic pyrethrum. BE CAREFUL IN CHOOSING A CHEMICAL MITICIDE IF YOU CHOOSE TO DO SO! Several miticides have DDT or fungal relatives that are toxic if inhaled by humans!
