What are Mites and How to Control in Your Garden

Eriophyidae, Tetranychidae

Mites are not insects – they are arachnids related to scorpions, spiders and ticks. There are about 3,000 species of mites in Australia involving many families. Many of the mites of concern to gardeners are members of two families:

Eriophyidae (includes Blister Mites and Rust Mites)
Tetranychidae (Two-spotted Mites).

Mites are very small creatures and some species (especially from the family Eriophyidae) can only be seen with a powerful hand lens or a microscope. Usually it is the damage they cause that you will see. Mites have piercing and sucking mouthparts which is how they damage plants.

Best Treatment for Mites

The secret to pest control is to keep an eye on your plants so that you can detect pest incursions early. This is especially important with pest mites because they breed very rapidly and infestations may build up quickly.

Keep an eye out for mite damage when working in the garden - you will need to know what to look for (see Symptoms of Mite Damage). If you find damage you should have a closer look to see if you can find some mites (see Description). This is quite difficult because many species of mites are about 0.2 mm long so you will need some kind of magnifier to actually see them.

Prevention is always better than cure, and you are more likely to be able to achieve that if you are out and about in your garden regularly. There are several things that you can do to prevent serious damage from Mites (see How to Prevent Mites Appearing).

Regular monitoring of your garden will make it less likely that a major infestation of mites happen ‘overnight’. All treatments are way more effective if you can catch an infestation in its early stages.

If you do find minor infestations of mites you can simply prune off the infested leaves, shoots or fruits. Take care not to inadvertently transfer the mites to clean parts of plants. You can put your prunings in a plastic bag and place it in the sun for a couple of days to kill the mites. Depending on the type of mite, there are also several products you can use to treat them (see Description).

What are Mites and How to Get Rid of Them

There are several types of mites that may cause damage in your garden. Common pest mites include Blister Mites, Camellia Tea Mite, Citrus Bud Mite, Citrus Rust Mites, Tomato Russet Mite and Two-Spotted Mites (aka ‘Spider Mites’).

Description:

Blister Mites (Eriophyidae) cause grotesque blistering on the leaves of various plants. They include Grapeleaf Blister Mite (Colomerus vitis), Hibiscus Erinose Mites (Aceria hibisci) and Lychee Erinose Mite (Aceria litchii). Blister Mites are tiny (less than 0.25 mm long), pale, torpedo-shaped creatures with four legs at the front end of their bodies. They do not have eight legs like other arachnids.

Products: Yates Lime Sulfur

Camellia Tea Mite (Calacarus carinatus) is also known as Ribbed Tea Mite or Purple Tea Mite. It is a member of the family Eriophyidae and is similar in appearance to Blister Mites except for its colour. It is a deep reddish-purple with white stripes – not that you will see that without a microscope!

Products: There are no treatments registered for camellia tea mite. The best thing to do is to remove as much of the affected growth as possible and feed the plant with a complete fertiliser, like Yates Thrive Roses & Flowers Organic Based Pelletised Plant Food to help the plant recover from the attack and to help strengthen it against future attacks.

above image of Camellia Tea Mite

Citrus Bud Mite (Aceria sheldoni) is found in all citrus growing regions of Australia and affect citrus fruit in particular. Citrus Bud Mite is a member of the family Eriophyidae and is similar in appearance to Blister Mites.

Products: Yates Lime Sulfur

Citrus Rust Mites cause brown russeting of citrus fruit. The Brown Citrus Rust Mite (Tegolophus australisi) is a native pest, while the Citrus Rust Mite (Phyllocoptruta oleivora) is introduced. Both pests are at their most serious in warm humid regions. Citrus Rust Mites are members of the family Eriophyidae and are similar in appearance to Blister Mites.

Products: Yates Lime Sulfur

Grapevine Bud Mite (a strain of Grapeleaf Blister Mite) feeds inside the buds of grapevines.

Products: Yates Lime Sulfur or Yates Mancozeb

Tomato Russet Mite (Aculops lycopersici) is a widespread pest of several solanaceous plants. Tomato Russet Mite is a member of the family Eriophyidae and is similar in appearance to Blister Mites.

Products: Yates Lime Sulfur

Two-spotted Mite (Tetranychus urticae) – aka ‘Red Spider Mite’ - is a serious and widespread pest of a wide range of plants. Two-spotted Mite adult females are about 0. 5mm in length, are yellowish-green with a large dark spot on each side of the abdomen and have eight legs. Males are smaller and narrower than females. Two-spotted Mites change colour to reddish-orange (hence ‘Red Spider Mite’) with the onset of cooler conditions.

Products:

All ornamentals and edibles: Yates Nature’s Way Vegie & Herb Spray, Yates Nature’s Way Citrus & Ornamental Spray or Yates Lime Sulfur

Roses and ornamentals only: Yates Mavrik

Citrus, shrubs and ornamentals: Yates White Oil or Yates Pest Oil

Citrus only: Yates Scale Gun

Life Cycle:

Mites have a life cycle of incomplete metamorphosis – there is no pupal stage. The entire life cycle can be completed in about a week during warm weather, and there are many generations per year. All stages of the life cycle may be present at the same time.

Eriophyidae: Eggs hatch into four-legged nymphs which moult into a second, larger nymph before a final moult to adult stage – all life stage only have four legs.

Tetranychidae: Eggs hatch into six-legged larvae and don’t develop the other pair of legs until they moult into nymphs. There are two eight-legged nymph stages – protonymph and deutonymph – before the final moult into the eight-legged adult form.

What Plants are Impacted by Mites

Grapeleaf Blister Mite cause blistering of grapevine leaves. A different strain of this mite known as Grapevine Bud Mite feeds in grapevine buds.
Hibiscus Erinose Mite cause blistering of hibiscus leaves especially in northern NSW and south-eastern Queensland.
Lychee Erinose Mite cause blistering of lychee leaves.
Camellia Tea Mite is a pest of tea (Camellia sinensis) and ornamental camellias especially japonicas (Camellia japonica).
Citrus Bud Mite and Citrus Rust Mites are pests of cultivated citrus.
Tomato Russet Mite is a pest of solanaceous plants including tomato, capsicum, and eggplant especially during hot weather.
Two-spotted Mite can damage fruiting plants including citrus, pome, stone and berry; ornamental plants including carnations, palms and roses; vegetables including beans, capsicums, cucurbits, eggplants and tomatoes; and they also breed in broadleaf weeds.

Symptoms of Mite Damage

Mites usually prefer feeding on young growth and will move up a plant when new growth becomes available.

Grapeleaf Blister Mites suck sap from the underside of grapevine leaves resulting in a whitish densely haired velvety area forming. Blisters form on the corresponding upper surface of leaves. The other strain of this pest, known as Grapevine Bud Mite, feeds in grapevine buds and may cause distorted leaves, damaged grape bunches, and even bud death.
Hibiscus Erinose Mites cause severe blisters to form all over hibiscus leaves – including the edges and both the lower and upper surfaces. Underneath each blister is a pale velvety area where the mites are feeding. Flowers may also be distorted.
Lychee Erinose Mites cause blisters that have a rusty velvety appearance (known as ‘erinose’) on lychee leaves, and may damage growing points and affect fruit set.
Camellia Tea Mites cause bronzing of camellia leaves, which is especially noticeable along the midrib. Mite infestation may also cause leaf curl. Camellia Tea Mites occur on both surfaces of leaves, and the leaves may have a ‘dusty’ appearance from mite cast skins.
Citrus Bud Mites feed in leaf buds, blossom buds and flowers of citrus trees. Damage includes distorted flowers, deformed leaves, reduced fruit set, and grossly distorted fruit.
Citrus Rust Mites cause russeting (brown stippling) of citrus fruits. Brown Citrus Rust Mite (Tegolophus australisi) cause russeting of fruit exposed to light – therefore, the outer parts of the tree. Citrus Rust Mite (Phyllocoptruta oleivora) causes russeting on the surfaces of fruit not exposed to light – therefore, the inner parts of the tree. Fruit may be reduced in size.
Tomato Russet Mites cause leaves to turn bronze, curl downwards and become dry (leaves crackle when crushed). Stems and leaf stalks become smooth (i.e. hairless) and brownish. Fruit may become corky, or be severely sunburnt because of lack of leaf shade.
Two-spotted Mites cause tiny yellowish spots on leaf upper surfaces from mites sucking sap on the underside of the leaves. Flowers and growing tips can be distorted and leaves may dry and fall. Mite webbing may form on the upper parts of plants. Plants may look drought affected or sunburnt.

How To Prevent Mites Appearing

Monitor

Check plants regularly for symptoms of mite damage. Use the information above so that you can detect mite pests early.
Any plant with distorted leaves, russeting, or containing obvious webbing should be investigated immediately.
Some mites such as Camellia Tea Mite, Tomato Russet Mite and Two-spotted Mite are favoured by hot dry conditions. Be particularly observant when these conditions occur.
A powerful hand lens may assist you in seeing mites.

Prevent

Maintaining plants in good condition may help prevent mite infestations, or at the very least will allow your plants to bounce back after an infestation. Water and fertilise your plants appropriately.
Control weeds. Two-spotted Mites are known to breed in a number of broadleaf weeds.
Be careful when moving among infested plants so that you don’t transfer mites to clean plants.

Natural enemies: