Banks Grass Mite – Oligonychus pratensis

Banks Grass Mite: Appearance, Territory, Damage, and Life Cycle

Latin Name: Oligonychus Pratensis

Appearance: The Banks grass mites (BGM), also known as Oligonychus pratensis (Banks), are tiny arthropods with eight legs that are 0.45 millimeters (0.017 inches) in length. BGM has dark pigmentation at the back and along the sides of the body. As their summer hosts, particularly field corn but also other grasses, start to dry out, fertilized female BGM move into winter wheat in the fall. These winter forms are a vibrant orange hue. They either travel small distances on foot to go back to the corn or travel vast distances on silk threads carried by the wind. Small pearly white eggs are deposited in the spring, and these eggs ultimately hatch into male and female adults that are a pale to brilliant green color.

Hosts Plants: The Banks grass mite has historically been a major pest of maize and sorghum, but it will shift to fall-sown wheat as summer host plants, including many grass species, begin to dry down.

Territory: Europe and the United States

Damage Insect Cause: The earliest indications of an infestation are frequently webbing on leaves and discoloration. BGM is most prevalent in the lowest part of the plant at first, and its density decreases as the infestation progress up the plant. Mites cause harm to maize and tiny grains by penetrating plant cells and draining plant fluids.

Natural enemies of the Banks Grass Mite include minute pirate bugs, predatory mites, and some lady beetles. Banks grass mite problems are frequently caused by the use of pesticides that kill these natural enemies but have no effect on the Banks grass mite. Sweet corn fields should not be planted near tiny grains, especially winter wheat. Large grassy areas around sweet corn fields will further enhance the danger of Banks grass mite infestations in sweet corn.

Life History and Habits: Females and eggs spend the winter in protected areas such as plant debris. They begin to emerge in the early spring. During the spring and summer, eggs are placed on the undersides of leaves and hatch in 3 to 10 days. The habitat of the Banks grass mite is similar to that of the two-spotted spider mite. When populations are large, the mites can be found open on a leaf or behind a protective silk webbing. There are several generations every year; one generation can be finished in 10 days during the summer. All stages of life can coexist on the same leaf.