Red Spider Mite

two-spotted spider mite(Tetranychus urticae). Most Red Spider Mites are actually Two Spotted Mites: pale greeny-brown in colour with 2 dark dots on their backs. Red Spider Mites are very tiny and generally live underneath leaves, getting worse in hot conditions.

These tiny, highly destructive pests are common in greenhouses and on house plants and can also be found on outdoor plants during the warmer summer months. In the greenhouse look out for them on tomatoes, cucumbers, melons, vines, carnations and chrysanthemums. Outdoors, you may find them on day lilies, gladioli, conifers and many tender plants .

Spider mites can be identified more easily by the damage they do than by their appearance. They pierce the leaf cells with their mouthparts and suck the plant juices resulting in discolouration of the leaves and sickly looking growth, and in worst cases the death of the plant. The leaf damage initially results in a fine brown speckling effect on leaves where the cells have died. The pattern of the mottling varies from plant to plant, but it typically starts on the underside of the leaves.

Webbing

When the infestation becomes advanced, fine webbing appears on new growth. Spider mites are arachnids (spiders) and can spin very extensive fine webs. The webbing acts to shield the colony like a blanket, and it also provides a series of ladders or netting which allow the mites to crawl from stem to stem. Where webbing is widespread the leaves will typically turn brown and drop off because of the extent of the cell damage.

Phytosieulus persimilis

These are tiny predatory beneficial mites, shiny orange and relatively fast moving. It eats both adult and eggs of the Two Spotted mite giving excellent control.

These predator mites need minimum 15°C but work best when temperatures are regularly 18°C to 22°C. This generally means application end April until September indoors, or June and July outdoors.

They work very effectively and can achieve a complete clean up in several weeks. Best results are achieved when following up the initial treatment with a second introduction two weeks later.

In the early summer it is a good idea to inspect vulnerable plants every week and deal with the first signs of mite infestation immediately. Where possible, remove infested leaves, buds and stems because this will initially reduce numbers. Spider mites prefer dry environments, so spraying the infested areas of a plant with water and damping the greenhouse floor areas will raise the humidity and hopefully slow the infestation rate.

Phytoseiulus are supplied in plastic tubes with vermiculite granules. They should be gently sprinkled with the vermiculite onto leaves half way up the affected plant; or if the leaf shape makes this difficult, the granules can be put into small cones of paper. The mites will move onto the plant in a matter of minutes and move around the plant looking for Red Spider mites to eat. On receipt of your order, please read the instructions before opening the tube! For more information about phytoseiulus click here