Spider Mites

Spider mites come from the family Tetranychidae, also classified as Arachnids, like spiders. Besides spiders, relatives to the spider mite include daddy-longlegs, ticks, and scorpions.

An up-close image of a spider mite with morning dew on plants.

Spider mites develop from eggs found near the leaf’s veins. Spider mite eggs are quite large, in fact, larger than the mother is. Spider mites are usually found in dry climates because they feed more under dry conditions.

Spider mites have eight legs and only a one-part body.
A spider mite alone is almost invisible to the naked eye; however, they can be seen in large groups. Also, when spider mites are in large groups, they can cause serious damage to crops and plants.

The mites have a pair of needle-like structures called stylets, which are used to split and break leaf cells. Spider mites push their mouth into the torn tissue and draw up the cell sap. The marks left on the leaf by the spider mite are quite noticeable due to the brownish or yellowish color. Quite often, the plant will die because of the damage caused by the spider mite.

Spider mites webbing can be easily confused with the webbing of a spider. A lot of spider mites produce their own webbing, especially when they occur in high populations. This webbing protects the mites and their eggs from their enemies.

The prime season for most spider mites is in the summer, and they can rapidly develop anywhere from a week or two weeks. For other species of the spider mite, the cooler seasons are their peak time. This includes the spruce spider mite and most mites that can damage turf grass.

Spider Mites Multiply Fast

Check plants regularly, because catching an infestation early matters. At the first sign, use the least toxic treatment that works, rinse the plants, and remove badly infested leaves.

Spider mites, by themselves, generally do not move much farther than from leaf to leaf. However, other forces like bird feathers, animal hair, and clothes often move them.

Some common plants that spider mites attack include muskmelon, cantaloupe, beans, blackberry, cucumber, melons, and tomato plants. The damage on the plant leaves often looks like yellowish specks and fine webs, and the plant and fruit growth is stunted.

Spider mites have a few natural predators, including lady beetles, lacewings, and predatory mites.

Do Spider Mites Bite Humans?

Not the way people fear, but skin contact is not always nothing. Spider mites feed on plants, not blood, and they cannot live on people. At the same time, readers of this page have reported itchy, flea-bite-like welts after working with heavily infested plants, and doctors have treated those reactions with antihistamines and cortisone shots. Brushing against a badly infested plant can leave irritated, itchy skin, especially in sensitive people. The fix is treating the plants and washing up after garden work, not treating yourself.

If you are getting real bites, especially at night in bed, spider mites are the wrong suspect. Look at bed bugs, bird or rodent mites (worth checking when a bird nest or feeder sits close to the house), or scabies, which a doctor can confirm with a skin scraping.

Spider Mites and Dust Mites Are Not the Same

People sometimes mix the two up. Spider mites live on plants. Dust mites live indoors in bedding and carpet, and they cause allergy symptoms rather than plant damage.