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Tree Mites (spider mites): Little tree pests

By: Lacey Russell, PhD | June 8th, 2018

Tree mites are tiny critters related to spiders. Because they are so small and often hide out in the shady spots in your plants like under leaves, they often go unnoticed until their population has exploded.

Tree mites are also called spider mites because the adults have 8 legs and spin webs like a spider. They have pointy mouthparts that pierce plant cells and suck out the juice inside.

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The adults are very small and spin a protective web of silk over large populations of the little plant suckers. They lay clear to yellowish eggs that are usually suspended in a fine web of silk on the undersides of host plant leaves.

The baby mites have six legs, and later develop into 8-legged nymphs. Many generations of mites can occur in one year. When heavily infested host plants decline, the mites spin silk threads and use these strands to passively “fly” or “balloon” in the wind to disperse.

Symptoms of Tree Mites 

Indications that tree mites, one of many tree conditions, are damaging your tree include yellow spots on the leaves that later turn bronze. On light to moderately infested leaves, stipples (spots) are concentrated around the leaves’ midrib and large veins. Leaves on more heavily injured plants can become yellowed, bronze, and fall off.

These mites also reveal their presence by leaving small webs between twigs.

types of spider mites and the trees they like

Spider mites feed on many plants such as fruit trees, vegetables, ornamental plants, and house plants, especially stressed plants. Adults and nymphs pierce plant cells and suck juice. They also feed on fruit, foliage and the even the roots of plants.

These mites tend to infest weak plants, so check to see what else may be ailing your tree. Good soil well drained soil and proper watering techniques will go a long way to keeping your tree healthy.

Pecan Scorch Mites

Mites are a problem on pecan tress. Pecan leaf scorch mites feed on the undersides of pecan trees. They suck plant sap and cause irregular brown spots on infested leaves.

The damage is often focused on the midrib or around large veins of the leaves. Damaged leaves appear to be yellowish-brown or scorched. Large infestations can cause leaf loss, especially if trees are under moisture stress.

Pecan scorch mites overwinter as adults in the rough bark of limbs. Adult females begin laying eggs in spring.

Scorch mites can complete a generation in 5 to 15 days and are more numerous during hot, dry weather. Natural enemies of scorch mite include predatory mite species.

Scorch mites prefer shady, interior portion of the tree. Significant damage can happen before infestations are noticed. Check the tree on the shady, lower branches regularly to detect an infestation.

Broad Mites

 This species of mite is known to infest pittosporum, apple, citrus, grape, pear and camellias, and azaleas. These mites are very small and cause damage to the leaves furthest from the trunk (the terminal leaves). They actually have a toxic saliva that causes twisted, hardened and distorted growth.

You may notice broad mites on the newest leaves and small fruit. When infected, the leaves turn downward and turn coppery or purplish. Flowers die and fall off as well. In fruit trees the damage is usually seen on the shady side of the fruit, so it’s not obvious at first.

Eriophyid Mites

These mites are different from other mites in that they only have four legs. They are slow moving and usually white to yellow in color and have a carrot shape to their bodies. There are hundreds of species of eriophyid mites that includes leaf-feeding rust mites and blister or gall-causing mites.

These mites are found living and feeding on the surface of leaves. They turn leaves bronze or reddish and can create galls on the leaves or witches’ brooms on the stems and flower buds. On evergreen trees, the needles turn yellow, curled and short. These mites can also pass diseases to the plant caused by a virus.

 Plants that affected by eriophyid rust mites include honeylocust, tomatoes, apple, bald cypress, citrus, junipers, and yews.

Other Kinds of Tree Mites

The gall-causing mites live on plants such as maple, ash, aspen, plum, elm, cottonwood, birch, hackberry, pear, apple, and all conifers, such as pine, spruce, juniper, and yew.

Other species of pesky mites include cyclamen mites that are often a problem in greenhouses that produce cyclamen, African violet and other ornamental plants

How to get rid of tree mites

If you notice mites on your trees or shrubs and the problem is not to large they can be eliminated by blasting water on the plant daily until the problem is gone. If the problem is larger, it's a good idea to contact a tree health specialist.

Natural enemies of mites also help to keep the problem under control. Their natural enemies include predatory mites, ladybugs, assassin bugs, wasps and other insects. These insects usually do a good job of keeping mite populations under control. However, if a problem does get out of hand, miticides labeled specifically for mite control are less harmful to these beneficial insects.

Because mites are not actually insects and are more closely related to spiders, mites are not killed by most insecticides. Often, their populations increase after insecticides such as Sevin dust are used because the beneficial insects, or predators of mites, are killed from the application.

The most important management tool for your landscape is you observing your tree health on a regular basis. A few things to make sure of:

  1. Properly water your soil by allowing it to dry out in between watering
  2. Provide your plants with rich nutritious soil
  3. Make sure your plants are getting the right amount of sunlight.
  4. Contact a tree health specialist for advice on maintaining a healthy landscape.

And always remember—if you find tree mites in your yard, make sure to let your neighbors know, so they can check their yard as well. These pests don't care about property lines. Neighbors joining together is the best way to keep trees and plants healthy.

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