Spider Mite Identification

The four primary species of spider mites that affect apples and pears are Two-Spotted Spider Mites, McDaniel Spider Mite, European Red Mite, and Brown Mite. The two-spotted spider mite (above) is distinguished by having only the two pronounced dark spots on the front part of its body, with no spots on the rear. Adult females for these two species overwinter in tree bark and emerge in spring when they begin feeding and reproducing.

Adult female European red mites appear red with long hairs that arise from white spots on the mites’ backs. Nymphs are typically green in color. Their eggs are red and slightly flattened. European Red Mite overwinter in eggs.

McDaniel Spider Mites have spots similar to the Two-spotted mite, but McDaniel Spider Mite has multiple pairs of spots, and unlike the Two-Spotted Spider Mite these spots also occur on the posterior portion of the abdomen. McDaniel Spider Mites overwinter as red adult females  under tree bark that emerge in spring and being feeding and reproducing.

Spider Mite Damage

All spider mite species cause very similar types of damage. They feed with piercing-sucking mouth parts which first causes whitish-yellow pots called stippling. As the infestation progresses, damaged leaves take on a bronzed appearance before turning brown, wilting and dying. In severe infestation the spider mites cover leaves and bud terminals with webbing. Mite damage decreases photosynthetic rates which indirectly cause yield loss, decrease quality and can also negatively affect the return crop.

Management

Natural predators are an important factor in keeping spider mite populations from growing out of control. Broad pesticides should be avoided, as they can harm natural predators, resulting in spider mite outbreaks. Commercially reared predators are available for release. The Western Predatory Mite (Galendromus occidentalis) or Neoseiulus californicus are able to control less severe spider mite infestations in most cases, without any pesticides needed. Predatory mites should be release in areas of the orchard where higher spider mites populations have been scouted. Multiple releases may be necessary to establish predator populations.

Cultural control aspects are also important for spider mites. Controlling dust, by applying water to roads and furrows can be helpful. Avoiding water stress on trees is also very important, because spider mites establish infestations faster on water stressed trees.

If chemical control is needed for severe infestations, be very careful to check the label of available products. Different active ingredients of miticides can be used to target different life cycles of spider mites. Different products will also affect other insects, such as natural predators, in different ways.

Learn More: Complete Guide to Spider Mites