Twospotted Spider Mite in Soybean
Published: 04/10/2026
Crop Damage
The twospotted spider mite (Tetranychus urticae) is a global pest of vegetables, ornamentals, and various field crops. In soybean, spider mite populations can become significant under hot, dry conditions, but are rarely a problem otherwise. Both immature and adult mites feed by piercing leaf tissue and sucking cell contents, reducing chlorophyll and photosynthesis. Early feeding produces yellow speckling, or “stippling,” which progresses to a sand-blasted appearance. Severe infestations cause leaves to turn brown and die.
Twospotted spider mite damage to soybean leaves (stippling).
Daren Mueller, Iowa State University, Bugwood.org
Pest Description
Adults are less than 1/60 inch long, cream to light green, with two distinct dark spots on each side and eight legs. Immature stages are cream-colored with six to eight legs, depending on the instar. Spider mites are arachnids, closely related to insects.
Twospotted spider mite with characteristic spots on each side of body.
Frank Peairs, Colorado State University, Bugwood.org.
Scouting
Begin scouting at field edges, particularly on plants with discolored leaves. Inspect lower, middle, and upper leaves for stippling and check the undersides for mites and their characteristic silk-like webbing. Shake leaves over white paper to detect active mites. Sample multiple field locations, as infestations may spread to green plants. Record the canopy location of colonies and the severity of stippling. Consider environmental and management factors when deciding on treatments:
Hot, dry conditions, south-facing edges, and sandy soils favor spider mite outbreaks.
Rain and high humidity suppress populations and enhance biological control, especially fungal pathogens.
Broad-spectrum insecticides can kill natural enemies and trigger population flare-ups.
Early detection enables targeted border or field-margin treatments.
Management
Exact economic thresholds for soybean are not established. The following damage rating scale can guide treatment decisions:
Rating Scale to Assess Damage by Spider Mites. Source: https://extension.umn.edu/soybean-pest-management/managing-spider-mite-soybean (Potter, B. and Ostlie, K. (2022).
Rating | Damage Observed |
|---|---|
0 | No spider mites or injury observed. |
1 | Minor stippling on lower leaves; no premature yellowing. |
2 | Stippling common on lower leaves; scattered yellowing on some plants. |
3 | Heavy stippling on lower leaves, spreading to the middle canopy; mites present in the middle canopy; some lower leaf yellowing and loss. This is the spray threshold. |
4 | Lower leaf yellowing is apparent; leaf drop is common; stippling, webbing, and mites are common in the middle canopy; minor stippling is present in the upper canopy. This is where economic losses begin. |
5 | Extensive lower leaf loss; yellowing/browning progressing into the middle canopy; stippling and leaf distortion in the upper canopy; high mite populations in the middle and lower canopy. |
Twospotted spider mites have been documented to be resistant to pyrethroids, carbamates, and neonicotinoids. For precise recommendations on scouting, treatment, and pesticide use, consult your local extension specialist.
Prepared and reviewed by Carol Pilcher and Robert Wright, with support from the United Soybean Board.
Twospotted spider mite damage to soybean leaves (stippling).
Twospotted spider mite with characteristic spots on each side of body.
Twospotted spider mite webbing.
Gallery images courtesy of Daren Mueller, Iowa State University, Bugwood.org; Frank Peairs, Colorado State University, Bugwood.org; Adam Sisson, Iowa State University, Bugwood.org.
This publication was developed by the Crop Protection Network, a multi-state and international collaboration of university/provincial extension specialists and public/ private professionals that provides unbiased, research-based information to farmers and agricultural personnel. This information in this publication is only a guide, and the authors assume no liability for practices implemented based on this information. Reference to products in this publication is not intended to be an endorsement to the exclusion of others that may be similar. Individuals using such products assume responsibility for their use in accordance with current directions of the manufacturer.
In accordance with Federal civil rights law and U.S. Department of Agriculture (USDA) civil rights regulations and policies, the USDA, its Agencies, offices, and employees, and institutions participating in or administering USDA programs are prohibited from discriminating based on race, color, national origin, religion, sex, disability, age, marital status, family/parental status, income derived from a public assistance program, political beliefs, or reprisal or retaliation for prior civil rights activity, in any program or activity conducted or funded by USDA (not all bases apply to all programs). Remedies and complaint filing deadlines vary by program or incident.
Persons with disabilities who require alternative means of communication for program information (e.g., Braille, large print, audiotape, American Sign Language, etc.) should contact the State or local Agency that administers the program or contact USDA through the Telecommunications Relay Service at 711 (voice and TTY). Additionally, program information may be made available in languages other than English.
To file a program discrimination complaint, complete the USDA Program Discrimination Complaint Form, AD-3027, found online at How to File a Program Discrimination Complaint and at any USDA office or write a letter addressed to USDA and provide in the letter all of the information requested in the form. To request a copy of the complaint form, call (866) 632-9992. Submit your completed form or letter to USDA by: (1) mail: U.S. Department of Agriculture, Office of the Assistant Secretary for Civil Rights, 1400 Independence Avenue, SW, Mail Stop 9410, Washington, D.C. 20250-9410; (2) fax: (202) 690-7442; or (3) email: program.intake@usda.gov.
This work is supported by the Crop Protection and Pest Management Extension Implementation Program from the U.S. Department of Agriculture’s National Institute of Food and Agriculture. Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and should not be construed to represent any official USDA or U.S. Government determination or policy.
USDA is an equal opportunity provider, employer, and lender.
©2026 by the Crop Protection Network. All rights reserved.
