Spider mites are persistent pests that can damage everything from your vegetable garden to your tallest evergreens here in the foothills of Colorado. These tiny arachnids do particularly well in hot, dry weather, making them a common problem for homeowners around the state.
When spider mites aren’t controlled, they weaken plants by feeding on their essential fluids. This leads to discolored leaves that often scorch and fall off. The good news is that by finding them early and taking the right steps, you can control spider mites and protect your landscape from excessive damage.
Key Takeaways
- Spider mites thrive in Colorado’s hot, dry climate and can damage a wide range of plants, from garden vegetables to large evergreens if left untreated.
- Look for stippling on leaves, bronzing of leaf edges, fine webbing, and premature leaf drop as signs of spider mite damage.
- Regular water spraying, especially on leaf undersides, can help control spider mites on smaller plants and create conditions that discourage infestations.
- Natural predators like ladybugs and predatory mites help control spider mite populations, so it’s important to avoid broad-spectrum pesticides that could harm these beneficial insects.
- For severe infestations, bring in professionals to apply miticides – a special type of pesticide designed only to kill spider mites.
What Are Spider Mites and Why Are They a Problem in Colorado?
Spider mites aren’t actually insects – they’re arachnids, like spiders, with eight legs and the ability to spin webs. They’re extremely small (usually no bigger than 1/20 of an inch), making them hard to spot without a magnifying glass. However, the damage they cause to plants is usually easy to spot.
Spider mites are a serious problem in Colorado, where hot, dry summers create ideal conditions for them. Without natural humidity to control their numbers, these pests can quickly multiply and spread throughout the warmer months.
For property owners around Jefferson County, effective spider mite management starts with knowing which plants are at risk, spotting problems early, and using control methods that are designed for our climate.
Types of Spider Mites in Colorado
Spruce spider mites. Image courtesy of Petr Kapitola, Central Institute for Supervising and Testing in Agriculture, Bugwood.org
Several species of spider mites are common in Colorado, and each one targets different types of plants:
- Twospotted Spider Mite: Often found in gardens, these mites target vegetables (like beans and eggplant), fruits (including raspberries and currants), and flowers. They get their name from two spots on their back that you can see under magnification.
- Spruce Spider Mite: These mites primarily affect evergreens like spruce and juniper. They’re most active in late spring and early fall, when they can cause significant damage if not addressed.
- Pine Spider Mite: These mites specifically target pine trees. When they feed, they cause needles to turn yellow or brown, which weakens the tree over time.
- Cedar Mite: Most often found on arborvitae and junipers, these mites cause browning that typically starts at the branch tips.
- Honeylocust Spider Mite: These mites focus on honeylocust trees, which are some of our most popular shade trees. They can cause leaves to yellow and drop early, affecting the tree’s ability to photosynthesize.
Other deciduous trees like elm, oak, and mountain ash can also be affected by various mites. Trees in drier locations are often more vulnerable, with aspen trees being particularly susceptible to infestations.
Identifying Spider Mite Damage
Twospotted spider mites on the underside of a leaf. Image courtesy of Whitney Cranshaw, Colorado State University, Bugwood.org.
Catching spider mite damage early makes it much easier to resolve. Here are the main signs to look for:
- Stippling on Leaves: Look for small, light-colored dots on leaves where spider mites have been feeding. This damage reduces the plant’s ability to produce energy.
- Gray or Bronze Leaf Edges: As the problem gets worse, leaves may develop a gray or bronze color, especially around the edges.
- Leaf Drop: Plants with severe infestations often start losing leaves, which can lead to major damage or plant death if the problem isn’t addressed.
- Fine Webbing: Spider mite webbing is finer than regular spider webs and tends to collect dust. If you see this webbing, it usually means you have an established infestation.
Simple Spider Mite Detection Tips for Homeowners
If you think your plants might have spider mites but aren’t sure, try this simple test:
- Place a white sheet of paper under a branch or leaf that you suspect may be infested.
- Tap the plant part gently over the paper – if you see tiny moving dots on the paper, they’re likely mites.
- For a better look, use a magnifying glass or your phone’s camera zoom. Adult mites have eight legs, while young ones have six.
- Make it a habit to check for stippling or webbing during midsummer when problems often start.
This quick check can help you catch problems early, making them much easier to handle.
Why Spider Mites Do So Well in Colorado’s Climate
Spider mites thrive in hot, dry conditions. These conditions stress plants and trees, making them more vulnerable to pest problems. In Colorado, where water can be scarce, many plants experience drought stress, creating an ideal environment for spider mite populations to grow quickly.
Adding mulch around plants helps keep soil moisture consistent and makes the environment less friendly for spider mites. Regular watering during summer is also important to keep plants healthy and better able to resist pest problems.
Natural Predators and Balanced Pest Control
Several natural predators help control spider mite populations, including:
- Ladybugs
- Big-eyed bugs
- Minute pirate bugs
- Predatory thrips or mites
However, these helpful insects are often harmed by common, broad-spectrum insecticides that people spray for other pests. When this happens, it can create a cycle where natural predators die off, allowing spider mite populations to grow unchecked.
For better results, consider using Integrated Pest Management (IPM) methods, which focus on targeted treatments only when needed. Natural predators are an effective way to keep spider mite numbers down, so it’s best to avoid widespread spraying that might harm them.
At LAM Tree Service, our plant health care specialists can recommend the best treatment options that control spider mites without harming the local ecosystem.
Use Water to Control Spider Mites
One simple but effective way to manage spider mites is using water to remove them from plants. Here’s how:
- Spray: Use a garden hose with a strong spray setting to treat affected plants. Focus on the undersides of leaves, where spider mites usually gather.
- Frequency: During hot or dry weather, spray plants every few days to prevent spider mites from returning.
- Timing: Water in the early morning or evening when it’s cooler to avoid stressing your plants.
Regular spraying breaks up webbing, removes mites, and creates conditions they don’t like. This method works well for smaller plants and shrubs near your home but isn’t practical for large trees.
Chemical Control Methods: Safe Use of Miticides
When water spraying and natural predators aren’t enough, miticides (pesticides specifically for spider mites) can be very effective. It’s important to select and apply these products carefully to avoid harming beneficial insects.
At LAM Tree Service, we use soil injection for serious infestations. This targeted approach puts miticide directly into the soil, where tree roots absorb and distribute the miticide throughout the plant.
Soil injections provide protection for 30-45 days and allow us to add plenty of water to the root zone at the same time. This helps keep trees hydrated so they can better resist spider mite damage. The combination of miticide and deep watering helps trees recover more quickly.
Since these pesticides don’t affect eggs, we usually need to reapply every 10 to 14 days until the problem is under control. Soil injections are more effective than foliar sprays because they need fewer applications and have less impact on the environment.
Pine spider mites. Image courtesy of Whitney Cranshaw, Colorado State University, Bugwood.org.
Smart Spider Mite Management: How to Prevent Future Problems
Keeping your plants healthy is the best way to prevent pest problems. Here’s what you can do:
- Avoid Too Much Fertilizer: High-nitrogen fertilizers can create soft, new growth that spider mites love. Use balanced fertilizers and follow the recommended amounts.
- Water Regularly: Plants stressed by drought are more likely to get spider mites. Use drip irrigation or soaker hoses to provide steady moisture, especially during hot, dry summers.
- Add Mulch: Organic mulch applied around trees and shrubs helps keep moisture in the soil and maintains more consistent soil temperatures, reducing plant stress.
- Reduce Dust: Spider mites do better in dusty conditions, so keeping plants rinsed and minimizing dust can help prevent problems.
Let LAM Help Protect Your Landscape from Spider Mites
When spider mite problems become too widespread for DIY solutions, it’s time for professional help. LAM Tree Service offers expert assessment and effective treatments, including soil-injected miticides for lasting results and healthier plants.
With early detection, balanced pest management strategies, and ongoing care, you can minimize spider mite damage and enjoy healthier, more beautiful plants and trees. Call us at 303-674-8733 to request an inspection and free estimate today.
