Acari : Tetranychidae

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Image above: Grass Webbing Mite webbing
(image courtesy of Scott Riley)

Grass Webbing Mites are silken web producing pests of warm-season grasses such as Buffalo grass, Couch and Kikuyu. There are a number of Grass Webbing Mites that occur in Australia, but the main pest species are from the genus Oligonychus. Grass Webbing Mites are found in eastern Australia including Queensland, New South Wales and Victoria. Grass Webbing Mites are sporadic pests that can be easily distinguished from other grass mites by the distinctive webbing they produce. The mites are often not noticed until the webbing becomes obvious.

Best Treatment for
Grass Webbing Mites

Grass Webbing Mites are only one of the pest mites that may infest lawns in home gardens. Fortunately, they are usually the least damaging mites that may affect your lawn. Like other mite pests, they are tiny creatures that are usually not obvious until their feeding damage has occurred. The webbing they produce does make them obvious but by then the damage has already occurred.

Grass Webbing Mites are usually more active in hot weather and they pass through their life cycle more quickly then. Consequently populations build up more rapidly and damage is more likely to occur during hot weather.

Prevention is the key to their control. A well watered and appropriately fed lawn is less likely to suffer from serious damage than a stressed lawn. If you suspect you have an infestation of Grass Webbing Mites, be especially careful when mowing the lawn as this may spread the mites. If you have to mow you need to catch the clippings, dispose of them, and then clean out the catcher.

There are no miticides specifically registered against Grass Webbing Mites in turf grasses.

To grow a healthy, strong lawn, apply Yates Dynamic Lifter Organic Lawn Food. It's a a slow release organic based fertiliser with the ingredients of composted manure, Blood and Bone, fishmeal and seaweed that improves the soil and fertilises the lawn. Suitable for use on all lawns, including Buffalo lawns.

What are Grass Webbing Mites &
How to Get Rid of Them

Grass Webbing Mites (Oligonychus spp.) may also be known as ‘Spider Mites’. They should not be confused with the more familiar Two-Spotted Mite (Tetranychus urticae), which is also known as Red Spider Mite. Grass Webbing Mites and Two-Spotted Mite are members of the same mite family Tetranychidae.

Two species (Oligonychus araneum and Oligonychus digitatus) have been recorded in Australia from a number of turf grasses, including couch, kikuyu and buffalo grass. Both these mites are native to Australia, and where they occur they are often found together in the same infestation.

Description

Adult Grass Webbing Mites are tiny eight-legged arachnids less than 0.5 mm long, making them barely visible with the naked eye. They are pale yellow green in colour and they have dark spots along each side of the body. Juvenile Grass Webbing Mites (nymphs) are smaller versions of the adults.

Grass Webbing Mite eggs are spherical and translucent white to yellow-amber but require a powerful hand lens to see.

Life Cycle

Grass Webbing Mites lay eggs on turf, which hatch and pass through four active life stages - larva, protonymph, deutonymph, adult. There is usually a resting period between each of these active life stages. The mites overwinter as either eggs or adult females.

Grass Webbing Mites become active in early spring. The mites can complete their life cycle in 8 to 25 days depending on the temperature and there may be up to 10 generations per year. As an infestation builds up, all stages of the life cycle may be present at the same time.

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Image above: Couch Mite infested lawn with ring shaped pattern
(image courtesy of Scott Riley)

What Plants are Impacted by
Grass Webbing Mites

Symptoms of
Grass Webbing Mites

  • Grass Webbing Mites pierce plant cells and suck out the liquid contents, causing chlorotic spots on leaves and eventually leaf dieback.
  • Large populations cause yellowing of grass in a ring shape, which turns brown and may be covered with distinctive protective webbing.

How to Prevent
Grass Webbing Mites Appearing

Monitor

  • Look for yellowing leaves, especially in ring shaped patches.
  • Check grass leaves for mites, especially on the underside of leaves near the base of the grass. The best way to do this is to pick off some suspect leaves and hit them against a white card or a light coloured container to dislodge the mites, which will then be visible as moving dots. A 10x magnification hand lens will allow you to see their eight legs and other features.
  • Look for webbing on lawns. Be aware that webbing may not be obvious when a mite infestation is in its early stages.

Prevent

  • Hot, dry weather is particularly favourable to mites and may also cause water stress in lawns. Water and feed your lawn appropriately, paying particular attention during hot, dry weather.

Natural Enemies

  • Predatory mites.

 


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