How to Get Rid of Spider Mites on Tomatoes
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How to get rid of spider mites on tomatoes starts with checking the undersides of the lower leaves. Spider mites are tiny, and the first sign is often a scatter of pale specks on the top of a leaf. Extension guidance from University of Maryland Extension and the University of Connecticut Integrated Pest Management program describes the same pattern: the pests live on the underside, the damage shows on top, and the fastest fix is catching the problem before the population grows. This guide walks through what the sources describe and where they stop.
Quick answer
- Check the undersides of the lowest tomato leaves every few days, since the highest numbers are usually there.
- Knock mites off with a firm spray of water, aimed at the leaf undersides, and repeat as the population returns.
- Look for natural enemies such as lady beetles, lacewings and predatory thrips, and avoid harming them when you act.
- Remove heavily webbed or yellowing leaves and keep the plant from drying out, because hot, dry conditions favor the pest.
How to recognize spider mites on tomato leaves
The sources describe spider mites as small pests that feed on plant sap. The University of Maryland Extension article on two-spotted spider mites explains that mites feed by sucking chlorophyll from the plant, which first shows up as small white or yellow marks on the top surface of the leaf. Those marks can look like other early leaf problems. Because the mites sit on the underside, the pest can build up for a while before most gardeners notice it.
The UConn IPM page on tomato spider mites describes the same feeding injury and adds that spider mite feeding can cause numerous yellow or white tiny, granulated spots on tomato leaves. As damage progresses, the leaf can lose color, yellow, brown and eventually die. The Maryland article notes that the mites occur in the highest numbers on the undersides of leaves, and that when populations get very high they can move to the top side of a leaf or onto fruit.
Webbing is another clue. The Maryland piece says that heavily infested leaves may be covered with very fine, irregular webs in which mites and eggs can be found. The UConn page says webbing on the undersides of leaves can appear when mites go unnoticed and their numbers become high. A leaf with fine webbing and a dusting of tiny moving dots is a strong sign of an active infestation. Hold a sheet of white paper under a branch and tap it to see whether small specks fall onto the paper and move.
Why the problem can grow fast
The main reason spider mites are hard to stop is speed. The Maryland article warns that current weather conditions can favor rapid mite development, noting that current conditions enables them to complete a generation in as little as 5-7 days, which could lead to a 50X increase in the population in just one week. A problem that looks minor on a Monday can be a serious infestation by the weekend.
The UConn page explains why hot weather matters. It states that when temperatures are above 80F and the humidity is below 90%, this is when reproduction rate will be the greatest making control difficult. A hot, dry tomato bed, a greenhouse or a sheltered spot against a wall can therefore favor the pest. The UConn page also notes that spider mites are more commonly seen in protective structures that limit rain splash on the leaves.
Webbing adds a second problem. The Maryland article says that once the spider mites begin to make these webs they are even more difficult to control, because the mites hide under the webbing and spray coverage becomes harder to achieve on the leaf underside. This is why early detection matters more than any single treatment. If you catch the mites when only a few leaves are affected, you have more options and less work.
To see how mites move through a planting, read our explainer on how spider mites spread across plants. For the feeding injury itself, see how spider mites pierce leaf cells to feed.
How we chose these steps
We limited this guide to steps that appear in extension or university integrated pest management material for tomatoes and vegetables. We picked the two sources above because one is a university extension bulletin on two-spotted spider mites in vegetables and the other is a university IPM page specifically on tomato spider mites. Both were opened on 2026-10-29 and both describe the same pest, the same leaf-level damage and the same first-line checks.
We left out steps that depend on specific products, dosages or timing schedules, because the sources we could read do not give home-garden dosages and because those details change by region and by label. Where a source describes a product class, we say so, and we do not present it as a recommendation for your garden.
Step 1: Scout the undersides of leaves
Start with the oldest leaves at the base of the plant. The Maryland article notes that infestations are highest on older leaves and at the base of the leaf near the petiole. Look at the underside of several leaves on each plant, not just the top surface. Mark or note which plants show stippling or webbing so you can track whether the problem is spreading.
A quick scouting routine helps. Check the same leaves each time, at the same point on the plant, and write down the date. If the number of affected leaves rises from one visit to the next, the population is growing and you need to act sooner.
Step 2: Knock mites off with water
The UConn IPM page lists high-pressure water among its management options. It states that physically spraying plants with high pressure water can help to dislodge the mites and reduce the populations. For a home tomato bed, this usually means a strong spray from a hose nozzle aimed at the undersides of the leaves. The goal is to move mites off the plant, not to soak the soil.
Water spraying works best early, because it removes a share of the population each time. A single spray does not account for mites that arrive later or for a population that was already growing, so plan to repeat the spray over several days and keep scouting between sprays. Do the spraying in the morning so foliage can dry before evening, and avoid spraying in the heat of the afternoon when leaves can be stressed.
Watering practice also matters. Keeping the plant from drying out reduces the hot, dry conditions the UConn page links to rapid reproduction. Water the soil at the base of the plant instead of relying on frequent light watering of the foliage.
Step 3: Protect natural enemies
The UConn page recommends that gardeners encourage natural enemies like lady beetles (Stethorus species), lacewings and predatory thrips. These insects feed on spider mites and can help hold a population down over time. The Maryland article describes predatory mites being used in greenhouse tomato and cucumber production, but it also notes that results depend on the initial pest population, temperature, humidity and cultural practices. It also says that several releases are usually needed for effective control, which is a point to keep in mind before buying any biological product.
In a home garden, the simplest step is to avoid actions that kill beneficial insects. Hold off on broad treatments when you see predators on the plant, and keep scouting so you can tell predators from pests. Flowers nearby may help support these insects, but the sources we opened do not measure how much a flower border changes spider mite numbers, so we do not claim a specific effect.
Step 4: Remove heavily damaged leaves
Once a leaf is heavily webbed or mostly yellow and brown, it is no longer feeding the plant well. Removing those leaves reduces the number of mites and eggs on the plant. Put removed leaves in a bag and dispose of them rather than leaving them on the soil under the plant. The sources do not describe a specific disposal method, so this is a sanitation step we are describing from general practice, and it is not a claim that the sources support a particular result.
Do not remove more foliage than you need. A tomato plant can tolerate some leaf loss, but stripping the plant to bare stems can stress it and does not solve the problem if mites remain on the remaining leaves.
Step 5: Watch the weather and the spread
Spider mites move from leaf to leaf and from plant to plant. The Maryland article describes that the pests can move up the plant and onto fruit when populations are high, so check the fruit as well as the foliage. Watch for a pattern: if the problem appears first on one side of a bed or on the plants nearest a sheltered wall, focus your scouting there and treat the area as the starting point.
Weather changes can make a difference. The UConn page links hot, dry conditions to faster reproduction. During a heat wave, plan to scout more often and to spray more regularly, because the population can rebound within days.
Common mistakes
- Checking only the top of the leaf, where the damage shows, instead of the underside, where the mites live.
- Waiting for heavy webbing before acting, since the sources say webbing makes mites harder to control.
- Spraying only once and assuming the problem is gone, when eggs and newly arrived mites can repopulate the plant.
- Ignoring predators on the plant and treating every insect as a pest.
What we could not verify
We opened two sources, and both are useful for identifying spider mites and for describing the first-line steps of water spraying and early detection. Neither source gave us a home-garden timing table, so we do not provide one. The Maryland article is written about high tunnels and greenhouse cucumbers and tomatoes, and the UConn page is written for a broader audience of growers and gardeners. We applied the general points to a backyard tomato bed and did not test them ourselves.
What the sources do not say
The sources we opened do not say how many sprays are needed for a given bed size, how long a population will take to fall after one treatment, or how often a home gardener should repeat water sprays. They also do not say how to tell which predator species are present in a specific yard. For product choices, dosages and timing for your region, consult your local extension office, which can point you to current guidance for your crop and state.
Frequently asked questions
What do spider mites look like on tomato leaves?
The sources describe them as tiny pests that feed on plant sap. Early feeding shows as small white or yellow marks on the top of the leaf, and the mites themselves are found mostly on the underside. Heavy infestations can produce fine, irregular webbing.
Why are spider mites worse in hot weather?
The UConn page says reproduction is greatest when temperatures are above 80F and humidity is below 90 percent, which makes control more difficult. Hot, dry conditions favor rapid population growth.
Can a strong spray of water help?
The UConn IPM page lists high pressure water as a way to dislodge mites and reduce populations. It is a physical method, so repeat sprays and scouting are needed to keep up with new mites.
Should I remove leaves with spider mites?
Removing heavily damaged leaves reduces the number of mites on the plant. Avoid stripping the whole plant, because the remaining foliage still needs to feed the tomato.
Do natural predators help control spider mites?
The UConn page lists lady beetles, lacewings and predatory thrips as natural enemies. The Maryland article notes that predatory mites are used in greenhouse production, but results depend on pest levels, temperature, humidity and practices, and several releases may be needed.
Sources
- University of Maryland Extension, “Expect to see two spotted spider mites on vegetables,” https://extension.umd.edu/resource/expect-see-two-spotted-spider-mites-vegetables (opened 2026-10-29).
- University of Connecticut Integrated Pest Management, “Tomato – Spider Mites,” https://ipm.cahnr.uconn.edu/tomato-spider-mites/ (opened 2026-10-29).
