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Bryobia praetiosa

Clover mite. Photo: Rayanne Lehman, Pennsylvania Department of Agriculture, Bugwood.
Scientific Name: 
Bryobia praetiosa
Common Name: 
Clover Mite
Growing Degree Days (GDD's): 
192–298 GDD's, Base 50F, March 1st Start Date. (Source: Cornell Cooperative Extension.)
Host Plant(s) Common Name (Scientific Name): 
Apple (Malus spp.)
Elm (Ulmus spp.)
Gooseberry (Ribes spp.)
Honeysuckle (Lonicera spp.)
Ivy (Hedera spp.)
Insect Description: 

It is currently thought that clover mites are a species complex: some may feed on grasses while others feed on woody ornamental plants and can have very different life cycles. Each can have a different scientific name than what is listed for this example. A specific subset of these mites may also be found inside homes but they do not feed on people, but rather enter the home to overwinter. The home environment is not suitable for them and they eventually perish, usually within a few days. Clover mites can become active as adults as soon as temperatures are above freezing. This species of mite becomes less active at temperatures above 70 degrees F and enters a summertime aestivation or type of dormancy. In general, many generations can occur per year, however this can vary between the different "species" within this species complex. Adult mites are flattened dorsally, 0.75 mm. long, and their first pair of legs can be longer than the other three. The front set are used to probe and search the environment. Eggs and newly hatched larvae are bright red but after they feed their color changes to a green/greenish black body with and orange tint and orange legs. When crushed, they leave behind an orange-red stain. Clover mites reproduce through parthenogenesis, or unfertilized eggs laid by females, and as such all adults are female.

Damage to Host: 

Leaves of plants become bronzed or silver in color.

Monitoring: 

Look for mites with magnification on plants that have been previously symptomatic early in the season, such as mid-late May or around 192 GDD's.

Cultural Management: 

Large populations of clover mites can be reduced by providing supplemental watering to areas where clover mites develop, such as dry areas at the base of sun exposed walls and around evergreens. Planting flowerbeds with plants that are not attractive to clover mites might be helpful, including but not limited to: geranium, chrysanthemum, zinnia, marigold, salvia, rose, petunia or shrubs such as barberry, juniper and yew (Gomez and Mizell, 2021).

Natural Enemies & Biological Control: 

Has important predators. Take this into consideration if selecting chemical management options on plants in the landscape.

Chemical Management: 

Abamectin (NL)

Beauveria bassiana (NL)

Bifenazate (NL)

Bifenthrin (NL)

Chlorpyrifos (N)

Chromobacterium subtsugae (NL)

Cyfluthrin (NL)

Cypermethrin (NL)

Deltamethrin (L)

Emamectin benzoate (L)

Etoxazole (N)

Fenazaquin (NL)

Gamma-cyhalothrin (L)

Hexythiazox (NL)

Insecticidal soap (NL)

Lambda-cyhalothrin (L)

Malathion (L)

Metarhizium anisopliae (robertii) (NL)

Neem oil (NL)

Spiromesifen (L)

Tau-Fluvalinate (NL)

Notes: 

The most effective applications for clover mites on landscape plants are made early in the season. Chemical management inside the home is not necessary or effective. Mites can be vacuumed up, but may leave behind red stains if crushed. (Note: clover mites do not bite people or their pets.)

Active ingredients that may be applied systemically include: Metarhizium anisopliae (robertii) (soil drench) and neem oil (soil drench).

When used in nursery settings, chlorpyrifos is for quarantine use only.

Make insecticide applications after bloom to protect pollinators. Applications at times of the day and temperatures when pollinators are less likely to be active can also reduce the risk of impacting their populations.

Note: Beginning July 1, 2022 neonicotinoid insecticides are classified as state restricted use for use on tree and shrub insect pests in Massachusetts. For more information, visit the MA Department of Agricultural Resources Pesticide Program.

Read and follow all label instructions for safety and proper use. If this guide contradicts language on the label, follow the most up-to-date instructions on the product label. Always confirm that the site you wish to treat and the pest you wish to manage are on the label before using any pesticide. Read the full disclaimer. Active ingredients labeled "L" indicate some products containing the active ingredient are labeled for landscape uses on trees or shrubs. Active ingredients labeled "N" indicate some products containing the active ingredient are labeled for use in nurseries. Always confirm allowable uses on product labels. This active ingredient list is based on what was registered for use in Massachusetts at the time of publication. This information changes rapidly and may not be up to date. If you are viewing this information from another state, check with your local Extension Service and State Pesticide Program for local uses and regulations.