Red spider mites are one of many members of the spider mite family, Tetranychidae.
Spider mites are a type of very common pest throughout North America and can wreak havoc on all types of plants.
They are especially problematic in a greenhouse and indoor house setting.
Spider mites are not insects; instead, as the name implies they are arachnids like their cousins: spiders, scorpions, and ticks.
Although spider mites are arachnids and closely related to spiders, they differ by not having two body sections but instead one section similar to a tick’s body.
How Can You Tell What Kind Of Spider Mites You Have?
Spider mites come in colors ranging from very pale to deep reddish-brown.
This distinction doesn’t help you much because they are so tiny you can hardly see them no matter what color they are.
Two types of mites are typically called red spider mites.
One is the European red spider mite, and the other is the southern red spider mite.
In the United States, we commonly see the southern type.
If you have red spider mites on your apple trees, they are more likely to be European spider mites.
How Can You Tell If There Are Spider Mites On A Plant?
Spider mites of any color, other than extremely pale ones, look like pepper or specks of dust.
If you suspect there are spider mites on a plant, shake a leaf or limb over a piece of white paper.
If tiny dots fall to the paper, you have spider mites.
In addition to being extremely small, they are hard to find because they tend to hide.
They stay in groups on the undersides of leaves where they use their piercing mouthparts to poke holes in the leaf tissue and suck plant fluids away.
When spider mites have been feeding on your plants, you’ll see tiny dots in the leaves.
If the infestation goes untreated, your plants’ leaves will become yellow, dry up and fall off.
Red Spider Mite Infestation Comes in Cycles
Spider mites are problematic when the weather is hot and dry.
In these conditions, they aggressively seek moisture from plants.
Red spider mite infestations are also likely in the autumn and early spring because these pests are more active when the weather is cool and dry.
This is when they tend to spread and windy weather spreads them more rapidly.
They swing from plant to plant on their webbing and also ride bits of webbing across the breeze.
This is why it’s so important to watch for them, treat them, and remove infested plants quickly and carefully.
Avoid letting the minuscule mites and their webbing blow off plants you are removing.
Cover the plants with plastic before removing them to contain the mites.
How Quickly Do Red Spider Mites Reproduce?
All spider mites reproduce very rapidly.
If you don’t notice spider mite populations right away, it’s easy for them to get out of control very quickly.
This is why it’s so important to inspect your plants frequently.
Turn over the leaves and look for dustings of spider mites as well as the fine webbing they weave over the surfaces of leaves.
Red spider mite eggs can overwinter on the undersides of leaves and the bark of plants.
Early in the springtime, as soon as the weather begins to warm up the larvae hatch and begin feeding.
After a few days, they look for a sheltered area so they can molt and begin their first instar.
Spider mite nymphs look like adults, but they are smaller than the tiny adult mites.
Altogether, red spider mite nymphs will molt three times before attaining full size and maturity.
This process takes a total of five days from egg to reproducing adult.
After the adult’s mate, the female spider mite produces eggs continuously and may lay as many as three hundred eggs in two weeks.
When the weather is hot and dry, the reproduction may be more rapid.
What Kind of Damage Do Red Mites Cause?
Even though spider mites are very tiny, they can cause a tremendous amount of damage.
Large infestations cause leaves to dry up, die, and fall off.
This naturally causes fruits such as melons and squash to sunburn.
Lack of leaves also very negatively impacts photosynthesis and can cause the entire plant to die.
On soft crops such as beans and peas, spider mites will eat the crop as well as the leaves.
On ornamental crops, spider mites destroy the appearance of the plant and may even kill it.
They are especially problematic on roses, camellias, and azaleas.
What Can You Do About Red Spider Mites?
The use of chemical pesticides is not advised because it can make a spider mite infestation worse.
Because these pests reproduce so quickly, they easily adapt to any chemical pesticide you may use.
This is why it’s so important to encourage natural predators in your garden.
In gardens where insecticides have been in use, spider mites are more problematic because they have no natural enemies.
Chemical pesticides kill off the tiny arachnids’ natural enemies.
Red spider mites are fairly well controlled by natural predators alone.
Keep a healthy population of beneficial insects thriving in your garden.
Purchase friendly fauna such as:
…and more from your local garden center or online.
Release these beneficial bugs early in the growing season before pests have a chance to get a strong foothold.
A healthy population of natural predators can help prevent heavy spider mite infestation.
Additionally, follow these good practices to prevent and deal with red spider mites:
- Keep plants well pruned. Plants with crowded leaves and stems naturally encourage all manner of pests.
- When you see evidence of spider mites, prune off the affected leaves and stems promptly. Cover them before pruning them to prevent the spread of the webbing and the pests.
- Dispose of affected plant parts in the trash or burn them. Never compost any material previously infested by red spider mites.
- Once you have pruned off affected plant matter, blast the remaining plants with a strong water stream from your garden hose. This will knock the pests loose and may drown them.
- Also, blast plants with a strong stream of water in a preventative manner. Having dust on plants leaves, stems, and fruit provide shelter for mites. Wash your plants every couple of weeks.
- Keep your plants well-watered. This will help prevent any type of spider mite infestation.
What If Red Spider Mites Have Taken Hold?
If you do have a heavy infestation of red spider mites, use a combination of natural deterrents as well as predatory insects.
A Neem oil solution sprayed on plants after pruning away affected foliage and blasting the remaining plants with water will help kill off any spider mites having managed to cling to the plants.
You should apply a Neem oil solution once every 3 – 5 days to kill off adult mites and eggs and interrupt their reproductive cycle.
When applying a Neem oil solution, be sure to spray every part of the plant, especially the leaves’ undersides.
It’s best to apply the solution in the evening when the temperature is less than 90° degrees Fahrenheit (32° C) and where the light will not hit the plants for several hours.
Use Chemicals Sparingly or Not At All
If you must use a chemical pesticide, be sure to use one mild and short-lived.
Apply it at dusk so it will not affect pollinators such as bees.
If you have fruit trees, it’s a good idea to apply a treatment of horticultural oil early in the growing season before the overwintering eggs have had a chance to hatch.
Remember these pests reproduce very quickly, so you cannot just treat once and consider it done.
You’ll need to use any treatment multiple times on 3 – 5 day rotating schedules to thwart eggs, nymphs and adult pests.