Spider Mites

The spider mite is a very common garden pest that can cause serious damage to your indoor or outdoor vegetable garden. These microscopic spiders are found on the underside of leaves. They extract fluids vital to your plants’ survival from the leaves, leaving noticeable traces of yellowish-white spots, known as stippling, on the top side of the leaves.

Further inspection of your plants should reveal tiny spider webs on stems and leaves. If you mist your plants, before inspection, it will make the webs easier to detect. With the use of a magnifying glass, you will be able to spot the yellow, white, brown, or red mites and their light-colored eggs.

PREVENTION

“An ounce of prevention is worth a pound of cure”, is what my grandma used to say, and she couldn’t have been more right if she had said the sky was blue. With very simple, preventative measures you can spider mite proof your indoor garden by making the living conditions inhospitable. Spider mites thrive in dry(20%-30% humidity), warm(70-80 degrees F) conditions. In temperatures above 80 degrees F, spider mites can reproduce in as little as 5 days, making early detection a necessity.

In order to make the environment uncomfortable for them, before and during the onset of an infestation, use a humidifier to raise the humidity in the room to around 50%-60% humidity and cool the room, with an air conditioner, to below 60 degrees F. This cool, moist air should drive away any spider mites.

Outdoors, it is impossible to control the environment, so in case of infestation insecticidal soaps, pyrethrum sprays and pyrethrin(all described later) should be used to keep an outdoor spider mite infestation in check. Always remember the best preventative measure you can take is checking your plants on a regular basis(every 2-3 days).

WHAT TO DO IN THE CASE OF INFESTATION

There are several ways in which to control a spidermite infestation, whether it’s in its beginning or if it’s a full blown infestation. Your first, but very time consuming, option is manual removal. This is only recommended for a very, very small infestation.

There are three options with a medium size nesting of spidermites; pyrethrum sprays, insecticidal soap and predatory spidermites. Pyrethrum and insecticidal soaps should be mixed according to their instructions and applied 2-3 times at 5-10 day intervals. Sometimes you might want to spray an extra time, in order to ensure you have completely rid yourself of these plant strangling pests.

Predator insects are being used more and more often, to help eliminate the populations of certain pests. Spider mites have two commonly used predators; amblyseius californicus and phytoseiulus longipes. When spider mites are first noticed in your garden, these predatory spider mites should be placed out at about 20 per plant(they must be placed on the individual plant because the predators have a hard time moving from plant to plant), or as many as you feel are needed and repeated once every month thereafter.

To give you a rough idea of how many predators you might need, 1(one) predator mite can eat 20 spider mite eggs or 5 adult mites in a day. Once the predator spider mites have depleted their source of food(spider mites), they will then die of starvation, leaving your garden pest-free, but repeated treatments may still be necessary

HOW TO CONTROL A COMPLETE SPIDERMITE INFESTATION

For a minor to medium infestation, pesticides and predators work well, but in case of a complete infestation, you should use pyrethrin. Pyrethrin is the most effective spider mite extermination product. After the first application, it leaves most adults and a majority of the eggs dead. 5-10 days later, after the second application, most of the newly hatched eggs(eggs hatch within 5-10 days) and the remaining adults are eliminated.

After another 5-10 days, another application is applied to kill any survivors(assuming there are any). Pyrethrin should only be used in severe cases. If you follow the necessary precautions and check your plants often, you should have no real spider mite problems. If you do, you now know how to contain, and eliminate them to avoid any real hazards to your plant’s health.

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