Spider mites can be serious pests of garden and greenhouse plants including trees, shrubs, vegetables and ornamental plants. The leaves of plants infected with spider mites first show small white flecks but as the infestation proceeds may become gray or bronze and eventually fall off. The loss of foliage stresses the plant and can result in its death.
Here are 10 interesting facts about spider mites that may lead to an understanding of the nature of the problem and its solution.
There are 1,200 species of spider mites.
Several hundred species of plants are attacked by spider mites including tomatoes, beans, roses, conifers, and oaks.
Spider mites are not insects, but are relatives of spiders, ticks, and daddy long legs.
A single female two-spotted spider mite (the most common kind) can produce about a million mites in a month or less.
Spider mites are about the size of the period at the end of this sentence and difficult to see. If you suspect you have spider mites, shake a branch or leaf over a sheet of white paper; if tiny moving specks appear on the paper you have spider mites.
Many spider mites produce silk webs that protect them against predators.
Damage from spider mites is caused when they puncture the plants cells to feed on the cell contents.
Many natural predators generally keep spider mites populations under control. These include lady beetles/lady bugs (Stethorus spp), minute pirate bugs, big-eyed bugs, predatory thrips, and predatory spider mites. Some of these are commercially available as control measures.
Dry hot weather favors the buildup of spider mite populations partially because it hurts their natural predators that need more humidity.
Use of insecticides against spider mites is often counter-productive because it kills the natural predators that normally keep spider mite populations in check.
The best way to control spider mites is through good cultural practices. Plants under stress are more susceptible to mite infestations than healthy plants so carefully watering and appropriate fertilizing will do a lot to ward them off. When mites are detected, try removing them with a strong spray of water. Avoid insecticides so as to allow the natural predators to do their work. If all else fails resort to a miticide but remember, mites, just like insects and other disease causing organisms, develop resistance to whatever is applied to them.
Karen Meyers