Do spider mites live in the soil? The answer is yes, they do, but only for a while. Most of their life cycle is spent on plants.
Spider mites are plant-eating mites that look like tiny spiders. Spider mites get their name from the way they spin webbing to protect themselves or as a way to protect their eggs. Spider mites thrive best when the humidity is low, so the drier your climate and indoor conditions, the more likely you are to have a spider mite problem. As long as their food source is available to them, these pests can live for as long as two months.
Spider mites commonly spin silk webs as they feed and move from plant to plant. This is a tell-tale sign of their presence. The webs are more commonly seen on the underside of leaves, but can also be found on stems and flowers. Spider mites suck the nutrients from plant cells through the leaves. Their feeding results in yellow or white spots on leaves; severely infested plants may have etiolated (yellowish) foliage with fine webbing evident between the leaves.
What Are Spider Mites?
Spider mites are part of the Tetranychidae family and are classed in the Acari (mite) order. They are not insects but arachnids, so they are more closely related to spiders, ticks, and scorpions than insects. Spider mites have four pairs of legs, two body sections, and no antennae. They have piercing mouth parts that enable them to feed on plant fluids as well as suckers that attach them to plants. They are very small, even as adults, and may be difficult to see without magnification. A spider mite’s body is oval and smaller than a pinhead. They can be red or green, and some appear transparent.
Once they have hatched from eggs, young spider mites go through three stages of development (instars) before becoming adults. The first instar is called a protonymph, the second a deutonymph, and the final stage a tritonymph. There can be between five and 17 days between each molt (shedding of skin), depending on temperature and how much food is available.
The most common spider mite pests in North America are the two-spotted spider mite and the carmine spider mite. The two-spotted spider mite is the most widespread with over 200 potential host plants, including vegetables, fruit trees and ornamental plants.
These mites can be difficult to spot because they’re so small — only about 1/50 of an inch long — and transparent. They have eight eyes and come in a variety of colors, depending on their diet:
- Greenish yellow with red or green spots if feeding on foliage.
- Red when feeding on flowers
- Brownish orange when feeding on carrots
- Carmine spider mites’ eggs may be white or red
Spider mites feed on the chlorophyll of plants. Spider mite populations can increase quickly, so it’s best to catch them early and treat them immediately.
Types of Spider Mite
Two-Spotted Spider Mite (Tetranychus urticae)
The most common species of spider mite is the two-spotted spider mite (Tetranychus urticae). It has two large dark spots on its body and is normally red or green with a yellowish underside.
As its name suggests, this pest has two large dark spots on its body and can be red, yellow, green or brownish in color. It feeds on over 200 different plants including tomatoes, beans, eggplants, potatoes, peppers, roses and many ornamental plants.
The life cycle of the two-spotted spider mite consists of egg, larva, nymph and adult stages. The eggs are tiny specks deposited in clusters on the underside of leaves. Female spider mites can produce up to 20 eggs per day during their two- to four-week lifespan. Eggs hatch into larvae in three to four days.
This stage molts twice before becoming a six-legged nymph. Nymphs feed for three to five days before becoming eight-legged adults that mate later that same day or the next day.
The two-spotted spider mite has several generations per year and overwinters as an adult in debris or under leaf litter around field borders or in greenhouses. Mites thrive in hot dry conditions with plenty of sunlight and low humidity: they prefer temperatures above 80 degrees.
- The spruce spider mite, found in the eastern United States, prefers conifers, especially spruce and fir trees.
- The European red mite is frequently found on apple and pear trees.
- The southern red mite feeds primarily on cotton, soybeans, and peaches.
- The strawberry spider mite damages strawberries in the winter and spring.
- The carmine spider mite attacks a variety of plants in warm climates (the adult female is reddish-purple).
How do you know if you have a spider mite problem?
Early signs of a spider mite infestation include:
- Small, faint yellow spots on plant leaves
- Foliage that turns yellow
- Leaves dropping early or prematurely wilting
- White or greyish webbing under the foliage
You can tell where spider mites have been feeding by looking for tiny white spots of dried excrement on the undersides of leaves. If you’re checking for spider mites on outdoor plants, look for signs of them on the south and west sides of the plant, where they’re most likely to be found.
If you suspect you have a spider mite problem, grab a magnifying glass and get an up-close view of your plant. You may see individual spider mites or their webs before you notice any damage to your plants.
Damages caused by spider mites
Leaves may have yellow or brown patches with tiny white spots. Spider mites also leave a characteristic stippling on leaves that looks like small dots. Leaves may drop early, especially when mite populations are high.
Spider mite damage is often confused with leafhopper damage or even nutrient deficiency, so it’s important to make sure that your plants do have spider mites before you begin treatment. To do this, look at the underside of a leaf using a hand lens or magnifying glass. If you see tiny moving dots that look like transparent spiders, your plant has spider mites.
Where Do Spider Mites live?
A lot of people have questions about whether or not two-spotted spider mites can live in the soil. They are a real nuisance in gardens and farms since they can kill plants by sucking out the fluids. They can also spread viruses among plants.
So, do spider mites live in the soil? The answer is yes, they do, but only for a while. Most of their life cycle is spent on plants. They can stay dormant in the soil for many months.
They feed on plant roots, as well as weak and dying plants. Spider mites are also known to feed on algae, bacteria, and fungi that are commonly found in the soil.
In my experience spider mites are more active during spring, summer, and fall, so if you can keep your plants clean during winter they may not survive till next year.
Spider mites that overwinter in the soil emerge in spring to feed on weeds or nearby plants until finding a host plant for reproduction. Spider mite larvae do not survive in the soil during winter.