Spider mite
Spider mites are small, plant-eating pests that belong to the family Tetranychidae, which are related to spiders and other arachnids. Notable for their ability to spin fine silken webs around leaves, these eight-legged creatures can significantly impact a variety of plants in orchards and greenhouses. They range in size from 1/50 to 1/20 of an inch and possess specialized mouthparts that enable them to pierce plant tissues and extract sap. Different species of spider mites can feed on a wide range of plants, including common crops like tomatoes, cucumbers, and various fruit trees.
Female spider mites lay translucent eggs, with some species producing summer eggs that hatch quickly and winter eggs that remain dormant until the following season. Management of spider mite populations often involves the use of pesticides, such as Acaricides, or biological control methods, like introducing predatory mites. Other preventive measures include applying neem oil or spray irrigation. Spider mites can reproduce rapidly, with some completing their lifecycle in just a few days, making timely control essential to protect affected plants.
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Spider mite
Spider mites are several species of plant-eating pests that live in orchards and greenhouses. These eight-legged relatives of spiders receive their name from their habit of spinning silken webs around leaves where they feed.
Kingdom: Animalia
Phylum: Arthropoda
Class: Arachnida
Order: Trombidiformes
Family: Tetranychidae
Genus: Various (see below)
Species: Various (see below)
This family of mites contains several eight-legged relatives of spiders and other arachnids. Two pairs of each tiny creature's eight legs are attached to the front of its pear-shaped, elongated, or stretched, body. The other two pairs of legs are located near the rear of the body. Some species have hooked claws. Several long hairs grow from the body and legs. Species range from 1/50 to 1/20 of an inch (2/5 to 1 1/4 millimeters) long. Females are usually larger than males. The largest species belongs to the genus Bryobia. Their colors vary depending on the species and season.
At the narrower head end of the body are the two pairs of mouthparts. One pair of jaws is called the pedipalps. These look like short legs and are sensory organs for finding food and handling it for the mouth. The second pair of mouthparts is the chelicerae. These are the sharp, needle-like jaws which pierce leaves and suck the juices.
The spider mite family contains several serious pests that eat plants and leaves of many greenhouse and orchard trees and plants. Each species may feed on different trees or plants instead of only one species, which is the habit of mite species in other families. Spider mites eat apple, pear, plum, peach, almond, elm, and damson trees. They may attack cucumber, tomato, blackcurrant, cotton, clover, pea, and alfalfa plants. As they eat, spider mites spin silken webs around the leaves, giving their name. These webs protect them and anchor their eggs to the surface of the leaves. A few species lay their eggs under rocks on the ground.
A female spider mite may lay up to 100 round, translucent eggs at two different times depending on her species and the climate. These are called either summer eggs or winter eggs. Early in the summer, she may lay summer eggs on the underside of leaves. These hatch a short time later during that summer, and the young become adults and are ready to mate within one month of hatching. Under other conditions, a female may lay winter eggs later in the summer. These eggs rest in crevices on stems and leaves and hatch the following spring or early summer.
The larvae, or young, from summer and winter eggs probably follow a similar growth pattern as other mites. The spider mite larvae have six legs when they hatch. They molt, or shed, their skins to become eight-legged nymphs. Nymphs may molt one or two times before they become adults.
Pesticides like Acaricides are one method of controlling spider mites. Another method is introducing mites from the family Phytoseiidae to an orchard or greenhouse which prey on spider mites. After killing and eating all the spider mites, the predatory mites die without spider mites to eat. Other methods of preventing or eliminating spider mites include using neem oil or Harpin Alpha Beta protein and regularly spraying plants with water.
The lifespan of some spider mites is around 2 to 4 weeks. Others require 4 to 5 days to complete a generation cycle.
Species include:
Banks grass mite Oligonychus pratensis
Cassava green mite Mononychellus tanajoa
Clover mite Bryobia graminum
European red mite Panonychus ulmi
Gorse spider mite Tetranychus lintearius
Red spider or two-spotted spider mite Tetranychus urticae
Spruce spider mite Oligonychus ununguis
Sugarcane mite Oligonychus sacchari
Bibliography
Anderson, Brianna. "Spider Mites: What to Know." WebMD, 16 Jan. 2023, www.webmd.com/a-to-z-guides/spider-mites-what-to-know. Accessed 15 May 2024.
"Spider Mites." Agriculture and Horticulture Development Board, horticulture.ahdb.org.uk/knowledge-library/spider-mites. Accessed 15 May 2024.
"Spider Mites and Their Control." Ohio State University, ohioline.osu.edu/factsheet/HYG-2012-11. Accessed 15 May 2024.