Clover mites (Bryobia praetiosa) are tiny—1/30 of an inch long and smaller than a pinhead—and bright red. These mites usually appear in large numbers in the early spring, and though they are more of a nuisance when they invade your home than when they invade your yard, they can to some extent also damage garden plants.
Clover mites feed on more than 200 different plant species, preferably on clover, which give them their name. Clover mites do not kill plants but when they feed on grass or leaves; rather, they suck out the sap, which can lead to a silvery discoloration.
The other type of tiny red bugs that you find primarily outdoors are red spider mites.
Learn what you can do to prevent and control clover mites, and how to distinguish between red spider mites and clover mites.
How to Get Rid of Clover Mites
Before you take any measure to get rid of clover mites, make sure that it is actually clover mites you are dealing with. Because they are so tiny, it is difficult to see their eight legs, including two front legs which are often mistaken for antennae. The easiest way to identify clover mites is to crush a few, which leaves a bright red, blood-like stain. Do this for identification purposes only and not as a way to get rid of them, because clover mites leave pesky stains.
If the clover mites are only present in your yard but not in your house, the infestation is considered low and the damage they cause on plants is limited and temporary. In that case, the next step is to take preventative measures so the clover mites won’t invade your home.
Only apply insecticides if the infestation is heavy or the clover mites are in your yard as well as your home. Any outdoor insecticide, however, will only prevent more clover mites from entering your house. Getting rid of an indoor infestation of clover mites requires a different treatment.
Select an insecticide for outdoor use that is specifically labeled to control mites. There are different products available that vary in the number of days the insecticide is effective after application. Follow the instructions on the label and apply the insecticide everywhere that you have detected clover mite infestations in your yard.
To prevent the clover mites from moving indoors when the weather gets cooler, also spray in a perimeter around your house. In addition, spray to the point of runoff around all the doors and windows, and as well as around the foundation and two feet high on all outside walls. Repeat the treatment as needed when more clover mites emerge in the late summer or fall.
What Causes Clover Mites
It is impossible to pinpoint where the tiny red bugs—clover mites are actually arachnids, not insects—are coming from other than that they appear when the weather warms up in the early spring. The mites overwinter in the egg stage in dry, protected places, such as sidewalk cracks, walls of buildings, and logs, then hatch in early spring. It is during that time that clover mites are the most active. After those early generations have laid their eggs, clover mites usually disappear until the temperatures cool down again in the late summer and fall. The eggs laid by the late generations hatch the following spring, continuing the cycle. Clover mites reach maturity in only 30 days, and one mite can lay up to 70 eggs.
Another factor that encourages clover mite infestations is excess nitrogen in your lawn.
How to Prevent Clover Mites
The first line of defense is a healthy lawn with just the right amount of fertilizer, as too much nitrogen attracts clover mites. Mowing your grass at the right height of three to four inches that allow root growth is equally important.
When you plant trees or shrubs, do not plant them close to the house, as clover mites like to crawl from branches onto structures. Shrubs should be planted at least half of the distance of their mature size from the foundation, so a 20-foot shrub should be planted at least ten feet away. If you have established trees or shrubs around the house, prune them to keep branches away from the house.
Also keep a plant-free and grass-free strip of at least three feet around the foundation of your house and cover it with mulch or gravel, which is difficult for clover mites to cross. Vegetation, dead or alive, on the other hand, serves as a highway to your home for clover mites. This includes leaf litter, which you should remove from around your house.
If clover mites are or have previously been a problem for you, select plants that they dislike and stay away from: annuals such as marigolds, petunias, and zinnias; perennials such as salvia and roses; and shrubs and trees such as barberry, juniper, spruce, arborvitae, and yew.
If you've had issues with clover mites moving indoors, make sure to seal any cracks or holes along windows, doors, or foundations.
Clover Mites vs. Red Spider Mites
Red spider mites also look like tiny red bugs to the naked eye, but the similarities end right there. Red spider mites cause much more and permanent damage on garden plants than clover mites.
There are two types of red spider mites. European red mites (Panonychus ulmi) mainly affect apple trees but also stone fruits and nuts. They lay their eggs in the bark and on twigs and branches of the trees where they overwinter. After hatching the mites feed on young leaves. With their piercing mouthparts they suck the juices and chlorophyll out of the leaf cells which leads to discolored bronze leaves. The mite generations develop in quick succession, especially in hot, dry weather. Each mite has a life span of about 18 days; if untreated, these mites can lead to heavy infestations, with the result of poor fruit color and stunted apples as well as damage to the fruit buds which will diminish the crop in the next season.
The southern red mite (Oligonychus ilicis) attacks a wide range of plants, edibles as well as ornamentals. Their preferred host are azaleas, hollies, rhododendron, camellias, and cherry laurel. They suck fluids out of the leaf cells, starting on the lower surfaces of plants. When populations are high, however, these mites will feed on the upper surfaces as well with the result of leaf discoloration, distorted leaves, leaf drop, and dieback. Southern red mites are cool-season mites that are the most active during the spring and fall when they rapidly reproduce. During the summer, they are dormant.
Because all three mites have numerous overlapping generations and they are so tiny, identification can be difficult. To distinguish the red spider mites from clover mites, the hosts they have invaded can give you clues. And then there is always the telltale sign of clover mites—the red stain that they leave behind when crushed.
Do Clover Mites Bite or Carry Diseases?
Clover mites do not bite and do not carry nor transmit diseases, so they are not a threat to human health.
How Long Do Clover Mites Live?
The life span of clover mites is about one month and there are five or six generations in a year. Egg-laying, hatching, larva to adult all take place in the spring or fall at temperatures under 85 degrees Fahrenheit. The larvae begin to feed on plants immediately after they hatch.
During the summer, clover mites are dormant. Egg laying in a protected, dry location continues when the weather turns cooler in the fall. Those eggs overwinter then hatch the following spring.
Will Clover Mites Go Away on Their Own?
Clover mites are a seasonal occurrence; they may or may not disappear on their own. However, a small infestation can lead to a heavy one, including clover mites in your home. If you spot clover mites in your yard, it is recommended that you follow all the preventative measures described above in order to keep them under control before they spread.