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Spider Mites

            

How to Get Rid of Spider Mites

Spider mites (Class Arachnida) are tiny sap-sucking plant pests. They attack the underside of leaves and suck the vigor from the plant; with large infestations they may even kill a plant. As soon as you spot an infestation, it's time to take charge and get rid of them!
Spider mites are spiders, not insects. They have 8 legs; insects have only 6. Regardless, they are a serious pest both indoors and out. Spider mites are very small, only about 1/50 of an inch long, and so are difficult to see. They have piercing-sucking mouth parts for feeding on plant sap. They can multiply rapidly and in large numbers, cause leaves to take on a dusty, dull appearance. Leaves then yellow and drop or turn brown or tan.

Enlarged view

Symptoms and Diagnosis

Since the mites are so small, the first sign is generally a plant that looks dull or in poor health. Leaves may appear stippled and curled. Fine webbing may also be evident under the leaves or between the leaf and the stem. When a leaf or branch is tapped over a white sheet of paper, small specks that appear as dust or pepper may be seen to move.

Life Cycle

Spider mites can go from egg to mature adult in less than two weeks. Indoors as well as outdoors, several generations occur each year.Adult female spider mites overwinter under loose bark, in cracks in the soil, in leaf litter, and in other protected places. In the spring, adults emerge and begin laying eggs. Each female typically deposits 70 eggs and lives for only 30 days. Eggs hatch in 57 days. As many as 10 generations may occur each year. The young look similar to the adults, but newly hatched young have only six legs and do not possess the characteristic dark spots on the back. Reproduction of the two-spotted spider mite is favored by hot, dry conditions, so serious damage is likely to occur in mid-July to September. The spruce spider mite is most active durng cooler weather in Spring and Fall.

 

Look at the surface of the leaves. If your plant is indeed infested with spider mites, the leaves may have yellow blotches on them. When light falls on the leaves, you may see a silvered look or even streaks of bronze or silver.

1. While mites usually attack the underside of leaves, they can sometimes get greedy and also eat the upper side of leaves and flowers. Eventually, the mites will suck holes right through the leaves - providing the most obvious evidence of infestation.

Even if you can't find holes in the leaves, your plant may still have spider mites, so keep an eye out for other signs of infestation.

Other signs of mite damage include distortion, deformation, wilting, spotting, streaking or discoloration on the surface of the leave. If the mite damage gets particularly bad, the leaves may start to fall off. 

2. Check for white webbing on the plant. This is a giveaway sign of some spider mites. The webbing usually clusters around feeding areas. Note that not all species of spider mite will produce webbing though.

3. Confirm the presence of spider mites. Spider mites are so small, they can be very difficult to see. However, one method you can use to confirm their presence is to take a sheet of white paper, place it beneath the plant you suspect to be infested and and lightly shake the stem of one of the leaves.

A certain number of the spider mites should fall onto the paper. They can be viewed more easily with a magnifying glass.

Spider mites come in a variety of colors, including red, green, yellow and brown. They have eight legs and tend to move quite slowly.

Be on the lookout for spider mites with spots on their backs - these are known as two-spotted spider mites and can be particularly hard to get rid of.

4. Be particularly vigilant with certain species of plants. There are some plants which spider mites seem to favor more than others.

In particular, pay attention to possible infestations on miniature roses, fruit trees, bananas, potted begonias, beans, mint, broad-leafed weeds, strawberries, frangipani and indoor houseplants.

Be aware that the two-spotted spider mite has been known to infest over 100 different species of plant.

Getting Rid of Spider Mites Naturally

5. Be especially alert during dry and dusty weather conditions. These are the conditions where spider mites can cause the most damage, as they are thirsty and are seeking moisture from the leaves of the plant. This also means they are very attracted to anything grown under glass, including plants sitting inside on your windowsills.

6. Wash and wipe indoor houseplants regularly. Given that it is fairly easy for the householder to clean indoor plants this way, it can be the most effective and non-toxic method to rid the plants of spider mites.

You can use either plain water or a solution of tepid (cool-warm) water mixed with a very mild dish detergent or soap. Any kind of soap can be used, but castile soap is particularly effective.

Use a sponge soaked in the water to wipe down individual leaves of the plant, or place the water in a spray bottle and spritz the underside of the leaves.

Apply the soap solution again, six days later, if the infestation continues. Be aware that some species of plant are particularly sensitive to soap, so consider testing the soap solution on a small section of the plant before spraying all over. 

7. Spray outdoor plants with a hose. Attach a spray nozzle to your outdoor hose and use it to water any infested outdoor plants. Set the water to a high pressure and try to target the underside of the leaves in particular. This should help to wash spider mites away. 

8. Use rubbing alcohol. Isopropyl rubbing alcohol will effectively kill spider mites. Simply pour a little of the rubbing alcohol onto a clean cloth and use it to wipe the underside of the infested plant's leaves. 

9. Use plant-based miticides. There are a number of commercially available miticides which use natural ingredients to kill the spider mites, but leave the plant and other insects unharmed. The three most popular ones are as follows:

Pyrethrum is a natural pesticide which is made from a plant closely related to the chrysanthemum. It is the best pesticide to start with when targeting spider mites, however some spider mite species have developed a resistance to it, so you should keep a close eye on plants even after spraying.

Cinnamite is a non-hazardous pesticide derived from cinnamon oil. Although it is very safe to use and is effective for killing the spider mites themselves, it will not destroy the eggs. As a result, it will need to be used approximately every 3 days over a two week period, to ensure that all of the newly hatched eggs are killed also.

Neem oil is a miticide derived from the nuts of the Neem tree. It is great for targeting infestations, but also works well as a mite repellent and a treatment for powdery mildew.

10. Remove badly infected parts of the plant immediately. Pick up any leaves that have fallen off the plant and pull off any badly damaged leaves from the plant itself. This will prevent the mites from affecting other plants nearby. Place the leaves in a sealed plastic bag and throw in the garbage or burn.

If an entire plant is infected, you should consider removing it completely. This will give other plants a better chance at survival.

Water affected plants only from above and keep removing any infected plant pieces as soon as you spot them. 

11. Control weeds around plants. Don't give mites extra hiding places and launch pads to attack the plants that you actually want to grow in the garden. In particular, remove all broad-leafed weeds.
Remove all debris remaining after harvest. This includes removing plant stumps, fallen leaves and any other plant matter. 

12. Use a homemade herbal tea. If you want to make your own miticide at home, you can make an herbal tea by mixing a tablespoon of ground cinnamon, a tablespoon of ground cloves and two tablespoons of Italian seasoning in a quart of water.

Bring the water to a boil, then take off the heat. Once it has cooled slightly add 2 tablespoons of crushed fresh garlic. Leave to sit until the water cools completely, then strain through a cloth or coffee filter.

Add a squirt of dish soap to the tea, then pour into a spray bottle. Spray the underside of the infested leaves with the tea every three days over a two week period. This should effectively kill the mites. 

14. Use essential oils and organic salts. Rosemary oil, in particular, is particularly effective as an organic pesticide. Try spraying a solution of rosemary oil and water onto the leaves of an infested plant.

Luckily, the rosemary oil will kill the spider mites, but leave the beneficial, predatory species of mites alone.[1]

Fatty acids or potassium salts can be abrasive against mite bodies. Apply these late afternoon, to give the maximum time for the wetness to remain on the plants, to get to the mites.

Mist susceptible plants with water in the evening to make the environment cooler and more moist. This works well for the two-spotted spider mites which prefer warm and dry environments. 

15. Encourage the presence of ladybugs and other insects which prey on spider mites. Predator insects, such as lacewing larvae, predacious thrips and ladybugs can decimate spider mite populations if encouraged to stay in your garden. However, one of the main reasons that spider mite populations develop in the first place is the use of pesticides which kill their natural predators. Therefore, you should avoid using pesticides such as carbaryl, malathion and imidacloprid.

Do not kill these

               

              This what they look like as babies (very desirable)

* These insects can be purchased online, from garden centers or through advertisements in gardening magazines. Alternatively, herbs such as amaranth and borage can naturally attract ladybugs into your garden.

* Ask the supplier for details on how to make the most of using predator insects, noting that you'll have less success if using them in a mixed planting area.

* Predatory mites can also be used against spider mites. Look for Phytoseiulus persimilis or other predatory mite species at the garden center (ask the retailer for the brand names it comes under, as this differs from country to country), then follow the release instructions.

* Under the right conditions, predatory mites can decimate a spider mite population. Interestingly, ladybugs (or ladybirds) will leave predatory mites alone, targeting just the spider mites!

Getting Rid of Spider Mites Chemically

16. Spray with an insecticidal soap indoors. Along with wiping the mites off with water, an insecticidal soap will take care of severe outbreaks.

17. Purchase a proprietary product suitable for outdoor spider mites. There are sprays or wipes available from garden centers and hardware stores. Use according to the manufacturer's instructions.

Dormant oil can be used in early spring, while light horticultural oil can be used in summer.

If spraying specific chemicals (such as dienochlor, dicofol, azocyclotin, fenbutatin, bromopropylate, propagate), it is recommended that you do not use the same product more than three times per growing season. This will help reduce the chances of the mites gaining resistance against the chemicals. 

18. Try getting rid of the mites with sulfur. Use either dusting sulfur or wettable sulfur. But don't use these in hot weather and be sure to follow the manufacturer's instructions.

Removal of Pests

1. Treat Entire Grow Area With Insecticide - Treat complete room with broad spectrum insecticide (only do this for a really bad problem, or one that keeps coming back) - avoid this if you can!

Note: Many growers try to avoid chemical sprays or miticides which contain Abamectin or lindane because these are harmful to humans.

2. Follow up in 2-3 days with a different method to kill them (you should also re-apply your first method)

Follow up in 2-3 days with something different that will also kill their eggs and any surviving adults. The adults at this point will already be more resistant to your original method so you'll get the best results using something else for the second treatment.

3. Repeat Step 1 & 2 at least one more time - always treat grow area at least once after you think spider mites are completely gone

4. Repeat steps 1 & 2 at least one more time to ensure that you have really cleaned out your grow room. Some species of spider mite can take days or weeks to mature and will reappear in the grow room stronger than ever. Because of this, you should treat your area at least once after you are almost certain all the spider mites are gone.

Using a mix of several different methods seems to work best for getting rid of spider mites. Some spider mites are more resistant to some methods than others.

If you can see spider mites with your eyes, it means you probably have millions in the room waiting to hatch.

Insecticides
Proven Spider Mite Remedies
(from serious chemical pesticides to organic repellents to home remedies)

Growers trust Spider Mite Killer
Spider Mite Killer blocks the breathing holes of spider mites, so they die by suffocation. It also deactivates the eggs and prevents hatching. Spider Mite Killer also causes reproductive disruption among female spider mites, leading to infertility or mites that don't develop to an adult stage.

Azamax is a time-tested way to rid your grow room of spider mites. Spray plants 15 minutes before lights out, making sure to drench the foliage under the leaves as well as the top of your soil. You may want to use a spray bottle or mister. Use a fan to blow on your leaves to help things dry. Treat your room more than once, even if you believe the spider mites are gone. You can also add small amounts of Azamax when watering your plants, as it will not hurt your roots but will kill spider mites in the soil.

Mighty Wash - use in a similar way to Azamax. You may want to use a spray bottle or mister.

Floramite - Strong stuff with harsh chemicals, incredibly expensive, but it can often do the job when everything else fails. Use as directed and only as a last resort!

Bleach solution (1 tablespoon of bleach to 1 gallon of 95F, pH balanced, water in a spray bottle or mister) - make sure to clean all surfaces of your room, and bleach them too if possible.

Alcohol and Water mixed together will also kill the bugs on contact and shouldn't hurt the plant as long as the solution contains at least 40% water. You will want to use a spray bottle or mister.

Neem Oil works in a similar way to SM-90, though Neem oil doesn't smell as nice and will leave an unpleasant taste/smell on buds when used to treat flowering plants. There's some evidence Neem oil may be harmful to humans so use with care! Just as with SM-90, you will need a mister to get all the leaves evenly, especially since neem oil and water will separate easily.

Cinnamite: A New Insecticide/Miticide
Cinnamite is a new insecticide/miticide labeled for greenhouse use from Mycotech Corporation. Derived from cinnamon oil, the active ingredient is cinnamaldehyde (30%). Cinnamite is labeled for use against mites and aphids, as well as powdery mildew. It is registered for use on a wide range of crops, including herbs. It has a 4-hour restricted-entry interval (REI). The material is effective against all stages of mites, including eggs, and it has demonstrated efficacy on green peach and melon aphid. The labeled rate for mites and aphids is 85 fluid ounces per 100 gallons of water. Cinnamite works by contact action only, so proper coverage of all plant parts is essential for control. It is fast acting and has short residual activity, which allows plants to be sprayed before shipping. The material has the added benefit of leaving the greenhouse smelling like cinnamon after use.

Insect predators - there are also insect predators such as lady bugs and predatory mites that can provide some control and reduce your spider mite numbers, but it is unlikely these will get rid of your spider mites on their own. Insect predators can be effective if you have a small problem or if you need to get to harvest and chemical sprays are not a good option.

Diatomaceous Earth - Basically, this is fossil dust - sprinkle on the top of your soil, and anywhere else in your room (window sills, doorways, etc). This powder-like substance is harmless to mammals and plants, but is incredibly sharp at the microscopic level. Therefore it will tear and dehydrate spider mites on physical contact. This will not get rid of an infestation, but can help control and slow things down when used effectively.

SM-90 mixed with water (1 part SM-90 to 5 parts water) kills spider mites on contact and is organic (it even smells good!). You will need a mister to get nice even coverage on all the leaves with SM-90.

Spinosad Products (safe & organic) - Spinosad products are organic and unlike many other spider mite pesticides, completely harmless to pets, children, and plants. Unlike many insecticides, you can spray spinosad heavily on leaves and roots with basically no negative effects. Spinosad products can be used directly to kill spider mites on contact, but can also be used when watering plants to systematically kill spider mites via the roots. Spinosad can also be effective at fighting caterpillars, thrips, and many other marijuana pests.

Can be used both as a topical spray like Azamax and Mighty Wash, and can also be used directly at the roots. Spinosad is an organic insecticide made from the fermentation of a specific soil bacteria (actinomycete Saccharopolyspora spinosa) and kills spider mites via ingestion or contact by effecting the insect's nervous system. Spinosad can be a good choice for organic and outdoor growers, because it is very toxic to spider mites, but is less toxic to many beneficial arthropods.

Note: Most spinosad products are effective for only about 24 hours after being mixed with water, so only mix as much as you will need per application. Anything left over will be waste. You will want to use a spray bottle or mister.

Doktor Doom Spider Mite Knockout Spray - This spray is hard on spider mites, but the main ingredient Pyrethrum can also be hard on plants, especially in tight spaces without much ventilation, so keep it as a last resort if possible. Use with extreme care around humans as the ingredients can be toxic. Never use Pyrethrum-based products on your plants while your grow lights are on as it can burn your plants. Avoid using Pyrethrum products on young or sensitive plants as they can get burned even when the lights are left off.

Do cover your lights and vents in the green house when bombing your plants with Pyrethrum and make sure you give the area at least 24 hours to air out before you try to breathe the air. This spray can work well for a couple of plants, but you'll want a Pyrethrum fogger if you have a lot of plants to treat. Outdoors, Pyrethrum can kill beneficial insects too, so keep that in mind if you're using natural predators to control pests (like ladybugs). All that being said, this spray will work to get rid of most spider mites, and it kills them on contact. Pyrethrum kills spider mites but not their eggs, so this product usually needs to be used 2-4 times (once every 2-3 days) to stop the breeding cycle and get rid of the toughest infestations.