Tetranychidae

Spider Mites

Subfamily Guides

is a of mites commonly known as , comprising approximately 1,200 described . Members are minute plant-feeding arachnids, typically measuring less than 1 mm in length. They are distributed worldwide and are significant agricultural pests, causing damage to hundreds of plant species by piercing leaf and extracting contents. Many species produce silk webbing for protection and . The family is divided into two : Bryobiinae and Tetranychinae.

Tetranychus urticae by (c) Aleksey Gnilenkov, some rights reserved (CC BY). Used under a CC-BY license.

Petrobia harti by (c) Julien Tchilinguirian, some rights reserved (CC BY), uploaded by Julien Tchilinguirian. Used under a CC-BY license.

Pronunciation

How to pronounce Tetranychidae: /ˌtɛtrəˈnɪkɪdiː/

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Identification

are distinguished from other mites by their small size (usually under 1 mm), two-segmented body plan (gnathosoma and idiosoma), and the presence of silk-producing glands. They possess eight legs in the stage and six legs as larvae. Many exhibit distinctive pigmentation patterns: for example, Tetranychus urticae has two dark spots on the , while Oligonychus pratensis (Banks grass mite) shows spots extending the full length of the body. Silk webbing production is a key diagnostic feature separating spider mites from many other plant-feeding mites. Species identification often requires microscopic examination of male and other genitalic structures.

Images

Distribution

Worldwide distribution with records from North America, South America, Europe, Africa (including Kenya), and Asia. Specific documented locations include: Texas High Plains, Winter Garden region, and Rio Grande Valley in the United States; Kenya in East Africa; Peru and Brazil in South America; and Scandinavian countries (Denmark, Norway, Sweden).

Diet

Herbivorous; feed by piercing plant with needle-like stylets and sucking cell contents. Documented include corn (Zea mays), cotton (Gossypium), apple (Malus), papaya (Carica papaya), passion fruit (Passiflora edulis), and numerous other crops and ornamental plants. Some are , with Tetranychus urticae recorded from over 200 plant species.

Life Cycle

Development includes , larva (6-legged), (8-legged), deutonymph (8-legged), and stages. In Tetranychus mexicanus, the egg-to-adult period averages 11.2 days on papaya and 12.0 days on passion fruit at controlled temperatures. times shorten significantly under warm conditions; elevated temperatures near windows can reduce generation time by more than half. Females deposit spherical eggs, often on silk webbing. Survival rates from egg to adult vary by plant, with 92% reported on papaya versus 79% on passion fruit for T. mexicanus.

Behavior

Males of some , including Tetranychus urticae, exhibit precopulatory guarding , remaining atop quiescent female deutonymphs for hours until maturity. Male recognition of female developmental stage occurs through chemical cues. Species produce silk from specialized glands, using it for between plant parts, protective construction, deposition substrate, and intraspecific communication. Under hot, dry conditions, increase rapidly and mites may move upward on plants, eventually colonizing all leaves.

Ecological Role

Significant agricultural pests causing yield losses through direct feeding damage during grain-filling and fruiting stages. Heavy can induce premature defoliation, stalk rot, and lodging in corn. Serve as prey for predatory mites (Phytoseiidae), minute pirate bugs, larvae, and lady beetles including specialized spider mite destroyers (Stethorus ). often follow broad-spectrum applications that eliminate natural enemies.

Human Relevance

Major economic pests of field crops, fruits, vegetables, and ornamentals. Banks grass mite and twospotted spider mite are principal pests of corn and cotton in the Texas High Plains. Control is complicated by resistance to over 95 and the slow action of modern miticides. Management strategies include conservation of natural enemies, proper irrigation timing, avoidance of excessive nitrogen , and use of selective rather than broad-spectrum . Drought-tolerant crop varieties show reduced mite growth under water stress.

Similar Taxa

Tarsonemidae (white mites)Both are minute plant-feeding mites, but Tarsonemidae lack silk production and have different body proportions; produce extensive webbing and have two pairs of eyespots in many .
Eriophyidae (gall mites and rust mites)Both feed on plants, but Eriophyidae are worm-shaped with only two pairs of legs and do not produce silk; have four pairs of legs as and produce characteristic webbing.
Phytoseiidae (predatory mites)Often found in association with as agents; distinguished by faster movement, different mouthpart structure adapted for , and absence of plant-feeding damage.