common name: southern red mite
scientific name: Oligonychus ilicis (McGregor) (Arachnida: Acari: Tetranychidae)

Introduction - Synonymy - Distribution - Description and Biology - Hosts - Economic Importance - Management - Selected References

Introduction

The southern red mite (SRM), Oligonychus ilicis (McGregor) is an important spider mite pest of broad-leaved evergreens. Bolland et al. (1998) reported the SRM from from seven countries on four continents and feeding on 34 different plant species in 15 families. The SRM is called the coffee red mite in Brazil.

adults

Synonymy

Oligonychus ilicis (McGregor) was originally described as Tetranychus ilicis by McGregor 1917, from American holly (Ilex opaca) in South Carolina. McGregor transferred the species to Paratetranychus in 1919 and Pritchard and Baker (1955) placed it in Oligonychus. The holotype is in the U.S. National Museum.

Distribution

The general distribution of the SRM includes the Northern Hemisphere and South America. Although the southern red mite was described in the United States, Pritchard and Baker (1955) suggested it might have originated in the "Far East." Published distribution records includes: Brazil, Italy, Japan, Korea, The Netherlands, Paraguay, and the USA. Although O. ilicis was reported from Australia (Knihinicki et al. 1999), the Australian Department of Agriculture, Fisheries & Wildlife reports it as eradicated (Anonymous 2006).

In the United States the southern red mite has been reported from Alabama, California, Florida, Louisiana, Massachusetts, New Jersey, New York, North Carolina, Ohio, South Carolina, and Virginia. It is probably widespread on broad-leaved evergreens in the eastern United States.

Description and Biology

The adult female is approximately 385 µ (1/50 inch) in length with a rotund-elliptical body. The adult male is approximately 300 µ in length, much less rotund, and narrowed posteriorly. The male aedeagus is shown below.. Both sexes are ferruginous to reddish brown, and darker than most red spider mites found on woody ornamentals. It is more translucent towards the front end of the body (Mizell et al. 2002).

life stages


Adult female: dorsal view.


Male aedeagus.

Numerous generations occur each year, but population densities are highest during the cooler months of spring and fall during periods of prolonged high humidity. The species overwinters as red eggs on the undersides of the leaves. However, darker, summer eggs can be abundant on preferred hosts when infestations are not controlled . While some mites may be active during the summer months, most of the population is dormant (in aestivation) during the summer heat (Johnson and Lyon 1994).

Hosts

Common hosts are azaleas (Rhododendron spp.) and camellias (Camellia japonica).

Other reported host plants include:

Economic Importance

This mite feeds primarily on foliage of woody ornamental plants. It is particularly a pest of azaleas and camellias. It usually attacks the lower leaf surface and as the population increases it will move to the upper surface of the leaves and on to small succulent stems. It injures the leaves causing a graying, stippling or mesophyll collapse, "firing," and defoliation. The leaves may be distorted if infested occurs when they are young and expanding (Johnson and Lyon 1994).

damage

damage

Southern red mite populations are at their peak during the winter months under mild, humid conditions. These mites can be found year round in the landscape, especially on eleagnus and on shaded or stressed pyracantha. Populations in the nursery usually disappear when the new spring growth develops (Mizell et al. 2002).

Management

Use a 10X to 15X magnifying glass to examine the undersides of the leaves for the mites, cast skins and their webbing. A quicker method that many employ is to place a sheet of white paper or paper plate beneath the leaves and strike the foliage sharply. If mites are present they will fall onto the white surface where they can be more easily seen and identified than on the green foliage.

Three different species of phtyoseiid mites were tested for predation of O. ilicis, with the adult females of the predators exhibing the most predation, preferring O. ilicis larvae over adults (Franco 2007).

Florida Insect Management Guide for ornamentals

Selected References

[The junior author thanks Dr. R.F. Mizell, UF/IFAS ornanmental entomologist, for his review of this updated publication.]

Authors: H.A. Denmark and W.C. Welbourn, Florida Department of Agriculture and Consumer Services, Division of Plant Industry; and T.R. Fasulo, University of Florida
Originally published as DPI Entomology Circular 79. Updated for this publication.
Photographs: R.F. Mizell and J.L. Castner, University of Florida; Frank A. Hale, University of Tennessee; Jim Baker, North Carolina State University
Illustrations: FDACS-DPI
Project Coordinator: Thomas R. Fasulo, University of Florida
Publication Number: EENY-376
Publication Date: July 2006. Latest revisionL December 2009.
Copyright 2006-2009 University of Florida

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