Spider Mites

How to Get Rid of & Kill Spider Mites

Early detection of spider mites is key to spider mite control. Checking once every week or every two weeks can help you track your spider mite levels. Here are some simple tactics in keeping spider mite populations under control. 

• Spraying plants and trees with a strong stream of water can knock spider mites off plants – the mites have difficulty finding their way back to the host plants. This technique also protects natural predators.
• Some ladybugs eat spider mites, as do thrips and predatory mites, and can keep populations low. Most effective are the predatory mites, which can be purchased and released onto host plants. Some predatory mites are host specific, and all vary under weather conditions – make sure you avoid using pesticides that could kill the predatory mites.
• Regular insecticides do not affect mites, so make sure you are using a product that acts as a miticide. Unhatched eggs are not affected by miticides. We recommend Talstar P for spider mites on non-edible plants; it is the most effective Bifenthrin product against mites. Spraying both sides of the leaves on the plants is the best way to use this product. It leaves a longer lasting residue than horticultural oils and insecticidal soaps.
• Horticultural oils and soaps are also very effective at killing spider mites, but must be applied while the mites are feeding, as they must coat the mites in order to kill them. Reapply often.

Spider Mite Life Cycle 

While there are many different species of spider mites, all go through the same development. The adult females lay eggs on host plants. These eggs hatch in March and April. The whole cycle of development can last from five days to three weeks, depending on species and weather conditions. Spider mite larvae have only three pairs of legs and molt into two nymph stages that last a few days each before molting into adults. 

Spider Mite Identification

Spider mites are a small, nearly microscopic but can cause huge amount of damage when in large numbers. Adult spider mites have four pair of legs, have no antennae, a single oval body (no distinct head), and have the ability to produce silk. In large-scale infestations the silk can be readily visible. To check if you have spider mites on your plants, the best way to check is to take a sheet of white paper and shake a branch over the paper. If the specks that fall on the paper start to slowly crawl across the surface, you are dealing with some kind of mite. Some species of mites can appear red, but all spider mites cause the same kind of damage, no matter the color.

Spider Mite Damage 

Spider mites use their mouthpieces to tear into leaves or veins in leaves or stems and ingest the cell sap. This makes the leaves appear to be “sandblasted” or stippled. Large scale infestations can cause the leaves to appear bronzed, bleached, yellow, or gray and untreated plants can lose vigor, get thinner, and could eventually die.

Spider Mite Host Plants

Spider mites that feed on conifers and broad-leaved plants are cool-weather pests that are most active in fall and spring. Spruce mites are very destructive and feed on conifers, spruce, fir, juniper, and sometimes pine. Spider mites that thrive in warmer months feed on linden, elm, willow, and oak among others. The most commonly destructive spider mite is the two-spotted spider mite. This mite has more than 180 indentified host plants and damage roses, violets, and other flowers, many garden vegetables, fruit trees, houseplants, and most greenhouse plants.