NC State Extension Publications

Description and Biology

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The privet rust mite, Aculus ligustri, is a microscopic mite with teeny-weeny, scissor-like mouthparts that it uses to puncture the epidermis of the leaves of ligustrum to feed. As privet rust mites feed, they inject their saliva possibly to help lubricate the mouthparts or possibly to predigest the tissue they are feeding on. Privet rust mites become active shortly after the leaves begin to develop in spring. The mites multiply rapidly on the leaves and green stems. Hot weather has a deleterious effect on the mite population perhaps because it favors the development of a parasitic fungus, Hirsutella thompsonii. Predaceous mites and insects are also more abundant in hot weather. Consequently in hot, humid weather, privet rust mite populations may drop to almost undetectable levels. During the warm summer period, these mites survive as aestivating females under old bud scales at the base of the current season's growth. With the advent of cool fall weather, the mite population begins to increase again. The typical life cycle of eriophyid mites includes an egg, two nymphal instars, and an adult stage. These mites can develop from eggs to adults in one week under favorable conditions. They can be distributed to other privets by wind, insects, and birds.

A typical eriophyid rust mite has only four legs at the front end (two on each side).

Rust mites are microscopic, cigar-shaped, and have four legs.

Illustration by J.R. Baker

Ligustrum showing some leaves damaged by privet rust mite (arrows).

Privet rust mites cause distorted leaves and eventual defoliation.

Photo by J.R. Baker

Privet rust mites ondicated with arrows

Privet rust mites on a distorted Chinese privet leaf.

Photo by J.R. Baker

Privet rust mites on stem at base of leaf petiole.

Privet rust mites on Chinese privet stem.

Photo by J.R. Baker

Privet rust mite on ligustrum bud scale indicated with an arrow

Privet rust mite on a privet bud perhaps seeking an aestivation site.

Photo by J.R. Baker

An eriophyid mite infected with Hirsutella thompsonii fungus.

An eriophyid mite infected with Hirsutella thompsonii fungus.

Illustration by J.R. Baker

Host Plants

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Eriophyid mites tend to be very limited in the plants they can infest. Privet rust mite infests Chinese and other privets. Their saliva has powerful enzymes that act as plant growth regulators on young leaves, causing leaves to become distorted as they enlarge. On older leaves, the damage is apparent as minute pale flecks or stipples, which, when abundant, give the overall shrub a grayish cast. Heavy populations of privet bud mites may cause premature defoliation.

Residential Recommendation

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Fortunately, privet rust mites are susceptible to the pesticides Sevin and Orthene. Sevin is readily available and not particularly toxic to humans and pets.


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For assistance with a specific problem, contact your local N.C. Cooperative Extension center.

This Factsheet has not been peer reviewed.


Professor Emeritus
Entomology and Plant Pathology

Find more information at the following NC State Extension websites:

Publication date: Nov. 5, 2013
Revised: Oct. 11, 2019

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