Eriophyid Mites

Order: Acari

Family: Eriophyidae

Description

Adults have cylindrical bodies that taper at both the head and rear. They are translucent white or yellow and have two pairs of legs near the head, unlike most mites which have four pairs of legs.

Quick Facts

  • The eriophyid mites are a group of arthropods that feed on plants and cause deformities. There are currently 1,859 species documented worldwide.
  • Eriophyid mites are extremely small and cannot be seen without a hand lens capable of 20x or greater magnification. Plant deformities such as curling or galls can be used as indicators of an eriophyid infestation.
  • Eriophyid mites are mostly generalists; however, some species are host specific. Other than cosmetic damage, eriophyid mites do not usually cause significant injury to trees.
Single eriophyid mite

Eriophyid mite adult.
Brian Kunkel, University of Delaware, Bugwood.org

Eriophyid mites include 1,859 species worldwide. These mites cannot be seen with the naked eye, however certain plant deformities indicate that an infestation may be present. These pests do not usually cause serious injury to trees.

Leaf curling caused by eriophyid mites

Whitney Cranshaw, Colorado State University, Bugwood.org
Leaf curling caused by eriophyid mites.

Leaf folding

Whitney Cranshaw, Colorado State University, Bugwood.org
Leaf folding caused by eriophyid mites.

brown finger galls

Bruce Watt, University of Maine, Bugwood.org
The brown finger galls are caused by eriophyid mites. The white stippling injury is caused by another phytophagous arthropod.

river birch with felt gall

Steven Katovich, Bugwood.org
River birch leaf with a felt-like gall caused by eriophyid mites.

Life History and Habits

Mites typically overwinter as fertilized adult females and emerge in the spring during bud break. After emerging, females lay eggs and begin feeding. These mites reproduce continuously, with a single adult female producing up to 100 eggs. Each generation completes development in 2-3 weeks; this high turnover results in overlapping generations.

Injury

Certain symptoms on the host plant can indicate a mite infestation. These include the formation of galls, fruit deformation and russeting, color changes on the leaf surface from bronze to brown or silver, leaf edge rolling, and folding of leaves. In the case of leaf curling, it is important to confirm the presence of eriophyid mites because certain herbicides also cause leaf curling. Eriophyid mites can only be confirmed with a microscope or high-magnification hand lens, which may require the assistance of an expert.

Galls are formed when plant tissues form pockets on leaves, stems, and flowers. In addition to eriophyid mites, there are several insect groups that form galls (e.g., aphids). During feeding or egg laying, these gall forming arthropods secrete chemicals that mimic natural plant growth hormones that stimulate growth of plant tissues. Eriophyid mites form finger-like galls, pocket galls, or masses of plant hairs on leaf surfaces that resemble the texture of felt. These structures provide protected feeding and development sites for the mites. More information on galls and gall forming insects is available here.

Cultural Control

Plants should be periodically examined to determine the presence of eriophyid mites before their numbers increase. In addition, some weeds can serve as secondary host plants, so removal of such weeds can help manage mite populations.

 

Chemical Control

Chemical controls should only be used when severe infestations cause major damage or tree stress. To help protect beneficial insects such as pollinators and natural predators of mites, consider using reduced-risk pesticides. If used improperly, broad-spectrum insecticides or miticides can kill off predator populations and lead to resistance in eriophyid mite populations. Therefore, broad-spectrum chemicals should only be used to quickly reduce mite numbers. For more information on reduced-risk and broad-spectrum pesticides, consult the Utah State University factsheet.

References

Davis, R. 2011. Eriophyid Mites: bud, bluster, gall and rust mites. Utah State University – Cooperative Extension. Available https://extension.usu.edu/pests/uppdl/files/factsheet/eriophyid-mites2010.pdf

Amrine, J. 2013. Eriophyid mites. Washington State University. Available https://s3.wp.wsu.edu/uploads/sites/408/2015/02/PLS-89-Eriophyid-Mites.pdf

Colorado State University. 2022. Eriophyid Mites. Colorado State University: Extension – Plant Talk Colorado. Available https://planttalk.colostate.edu/topics/insects-diseases/1400-8-eriophyid-mites/

Cranshaw, W. 2013. Insect and Mite Galls. Colorado State University: Extension – Fact sheet 5.557. Available https://extension.colostate.edu/topic-areas/insects/insect-and-mite-galls-5-577/